In addition to the stuff that shows up online only being the "leftovers" that were not snagged by ongoing, automatic searches, you will find that, to usually get anything desirable, planning well in advance is necessary with RCI (or almost any timeshare). You noted little was available for the rest of 2018. That's because most of the desirable 2018 weeks were booked well back into 2017. With our Marriott and HGVC timeshares, we're booking stuff for early 2019 now, and have had an ongoing search in place for a fall 2019 trip since fall 2017 (using the other exchange company, Interval International, with one of our Marriott weeks).
Also note that the vast, vast majority of the resorts in RCI will not be as nice as HGVC. In RCI, HGVC and the Disney Vacation Club are basically the cream of the crop. There are other nice resorts, but those are dwarfed in numbers by the marginal ones. Even the RCI "Gold Crown" designation is no guarantee of quality in line with HGVC. I've stayed at a couple Gold Crown RCI properties that were nowhere near HGVC quality. Based on that, I would hate to see what some of the non-rated properties in RCI are like.