Hello,
I suspect from your comments that you work for Hilton. But just in case I'll go through the reasons when to and when not to buy from the developer for all major brands.
Hilton: no developer perks of value (*story about elite bands at the end of this post). Huge discount buying resale outweighs initial purchase points, even in NYC as noted above. I think HGVC is a great product (to purchase resale) because of the flexibility.
Marriott: There is no cheap access to the points system. Some tuggers advocate purchasing a combined week/points package from sales. I think (if you MUST have MVC points) the optimal decision is to buy the smallest possible points package resale and then rent in points for slightly more than the points MF. You would never recover the purchase price of developer points compared to this method unless you absolutely always work the perks (13 month is unreliable, would need to make it up on discounts). For many/most, legacy resale weeks will be the optimal choice. It has less access to their newest "resorts" but those are basically all hotels. If you want a hotel book priceline or similar.
Hyatt: pure points is a tire fire. The legacy points system is complicated but works well, and transfers with resale weeks. Resale weeks are WAY cheaper than developer weeks, even in their top tier locations like Maui. Incentives don't make up the difference.
Vistana: the staroption system is open to resale owners. Also, both westin and Sheraton flex can be purchased resale. Huge discounts available for exactly the same thing. IF someone happens to travel a lot in Marriott hotels (but not so much they have status) AND has the time to travel to Vistana timeshares, it might make sense to buy large Vistana deeds resale. Then trade some in on small upgrade purchases to requalify he remainder. I think this is poor value, but the perk isn't otherwise available.
Holiday Inn: points are available resale at certain resorts. Perks are significant, but so is the purchase price. Many of the "signature" resorts can be substituted by trades to nearby resorts, or into weeks owned by legacy ownerships at the same resort. The value of the perks/incentives doesn't justify buying developer.
Worldmark: the perk for buying developer is called travelshare. The stuff that comes with it can be acquired cheaper by buying it. It also comes with club pass (aka access to leftover wyndham units) if that is a big value buy a wyndham deed, otherwise trade with a wyndham owner who wants worldmark access (I've done this, it works). Super-duper elite level (73k developer) comes with free housekeeping, but that perk can be acquired over 100k cheaper by buying a grandfathered no housekeeping resale. Resales come with everything else at huge discounts. Worldmark has higher resale than almost any other system and the incentives aren't even close.
Wyndham: the perks for buying developer are VIP. The discounts have some value for last minute booking. They recently neutered VIP by cancelling a sales-promoted tactic called cancel-rebook, which is a good reminder that the non-deeded "perks" that come with developer purchases can be changed or cancelled at any time. The deeded stuff that is guaranteed comes with a resale. For the vast, vast majority of people resale is better here. It's way cheaper (95%+) and you have to work the discounts to justify VIP big time. I think it probaby only makes sense if your buy tons of resale points and rent out. Some tuggers got VIP with resale in the past (as far as I know that isn't possible now - if it is I'd love a PM) but you can PIC resale weeks through telesales to get it at lower cost. It still never makes sense to buy at a resort.
Shell - points are free with free usage resale. Developer perks are not meaningful.
Diamond - The Club is only available developer. I think the value here is poor, and the benefits of The Club don't outweigh the massively increased cost of buying retail (or upgrading via retail).
Welk - points are available resale. The cheapness of resale points outweighs incentives/perks.
Bluegreen - resale owners need to be careful which trust/type they buy, but given resales are free/cheap this restriction is minimal, imo.
Breckenridge Grand - resales are way cheaper. Biggest developer perk is day use for skiing. My understanding is that everyone gets it at their original resort so buy resale there if that is important (check this before buying, I don't own here).
Disney - Significant disney related perks for buying direct. Most notably access to the Gold annual pass. Not applicable for FL residents who can get it anyway. If you would otherwise buy annual passes at regular price AND a DVC resale, a small developer purchase may make sense. You should do a spreadsheet of total cost of both options for the life of the contract. If you assume a reasonable rate of return on the extra initial capital it isn't a slam dunk. Anything more than the minimum should be purchased resale.
Grandview - great rci points units available resale at 90% off. Buy that not developer. Not even close.
Anyway, in the spirit of analytical dialogue I've tried to be comprehensive. Since you have so far declined to state who you work for (your prerogative) I've summarized the case for buying resale/developer for every brand I could think of.
If I missed some or you'd like to discuss one of them in further detail let me know. I'd be happy to spreadsheet out the details on any of my assertions. I'm on my phone right now or I would have done a more complete analysis.
**almost forgot - I stayed at HGVC Kings Land last week. Two bedroom unit in phase 1, which I believe is 9600 HGVC points. I traded in through RCI with a timeshare I got for free. The MF is ~600, well under the MG of a Kings Land unit. But it gets better - I got the timeshare free with 1 years free use. This was the free (seller paid incentive) use. So my only cost was the RCI exchange fee, that I got 25% off of for making a deposit (RCI Pro), plus the resort fees/taxes ($286/week).
I couldn't help thinking when I saw folks wearing the "elite" wristbands that they looked handy for not carrying a key card. I estimated the value to me at $20 though, not $50,000....