Unless they end up with exactly 1,000,000 VIP eligible points, they would actually be getting an additional 20 guest confirmations, not 5. At 1,001,000 points, you get 30 guest confirmations. So 20 guest confirmations per year, if you use them, is worth $2,000 a year.
And that is where the deal has merit.
Also the difference between platinum and gold at a million points is more than 150 000 points. The Platinum turns it into 2 million where gold is just over 1.5 million.