I guess OP is suggesting there may be better ways to book hotels, from the hotel chain’s own channels that’ll ensure you earn points and stays and your status is recognized, stacking those official channels with cashback portals like Ebates; or through other OTA like Hotels .com, where you can often buy their GCs for like 10% off, or Orbitz that has discount codes.
This promo requires you to book through the Chase travel portal on the CF/CFU, and pay cash, not UR points. Although that’s now essentially Expedia, we’ve seen Chase’s UR portal is not the Expedia available to everybody. And Chase’s hotel prices may be more expensive than other channels, whether the hotel’s own or from other OTAs, so you need to do your research to be sure you’re getting a good deal even with the 10x UR.
The cryptic reply, and the follow-up to that comment seems to be in reference to the peculiar way refunds of purchases under the CF’s 5x UR bonus categories codes. If you pay for something under the CF’s bonus category, you earn 5x UR on the purchase; but if you have to return it, Chase will refund the purchase amount but only deduct 1x UR back, essentially letting you keep 4x UR. This may not be well known, but it’s not super secret stuff and Chase may at some point fix it (if it hasn’t already). I think that poster might be suggesting the 10x UR bonus could work the same way if done on a CF. However, as another comment notes, most prepaid bookings aren’t cancellable; and most cancellable bookings don’t involve any prepaying, so the cancellation isn’t a transaction that’s visible to Chase to credit you or refund. You might be able to try this with a hotel that requires a deposit, but lets you cancel for a refund of the deposit. But even DoC chimed in that he wouldn’t recommend it.
(To be clear—while this is the way refunds coded on CF’s 5x categories as recently as a month or two ago, I could’ve sworn I saw a DP recently that said Chase took back the full 5x on a refund. I can’t find that DP so I don’t know if Chase has fixed this glitch or not.)