TBH this wouldn't shock me. I want to say that I've seen a few places (generally off-brand) going back to Visa/MC-only. Amex is also a bit more aggressive with their fees, so there's a possible one-two punch (since it is quite possible that aggressive disputes could add up to a significant share of a percent of a business's turnover with Amex's policies). By comparison, Chase is prone to granting disputes - but they only throw out the amount being argued over, not the whole amount.

So while on a week-long stay at $400/night plus a $40 resort fee, my (implied) experience is that if you decide to dispute the fee (say that most/all of the stated benefits weren't being provided - this was an issue with some Marriott properties when Winnie the Flu came to town: The fee was [allegedly] to cover the gym, pool, park shuttle, etc. at one hotel but all of those things were shut down for several months, only leaving the wifi) Chase would kick the $280 while Amex would at least temporarily kick the whole $3000-ish charge.

Now, I feel like a $3000 charge for a hotel franchise owner is more likely to get a response on the dispute than a sub-$200 charge from a (probably) larger company (or a $5-10 dispute over a hidden surcharge) - I've filed a few of those in the last year or so since some places have gotten a bit too sneaky with that sort of thing), so the $3000 might not stay off, but having that much in limbo for a month or two isn't going to do anybody's cash flow management any favors...and if something like that becomes a frequent basis for disputes, it could easily turn into regularly having tens of thousands of dollars ending up tied up at times. Even if every one of those disputes is resolved in their favor, the hassle and so on is definitely something that will get somebody's attention.