As somebody who prefers to play smaller PC releases natively on the Mac when they're available (and up to this point, most of them were)—it's a matter of personal convenience—you can't imagine how relieved I am that most of that ecosystem also migrated to the Switch within the past year or two.
The 32-bit transition had to happen sometime, but the incompatibility horizon introduced by Catalina is a problem to the point that publishers have been delisting Mac ports from storefronts, even for those of us staying on Mojave for the 32-bit support. I've been combing through a lot of older Steam listings due to the giveaways thread, and it's staggering how many titles used to have cross-buy/SteamPlay support but don't any longer, because Aspyr and Feral don't want to sell 32-bit-only software to post-Catalina users who can't play it (for obvious reasons), nor do they want to go back to maintain it.
Apple has never had a clue about games on Mac. It used to be that we could blame this on a blind spot of Steve Jobs', because what Jobs doesn't see, Apple doesn't do. But they're well out of excuses by now. And it's clear that the move from OpenGL to Metal (another thing they needed to do but put off far too long) didn't do the job they wanted, of having the viability of Mac games piggyback off the popularity of developing for iOS. Among the big players, it's only really Blizzard building Metal engines for their back catalogue.
The next big incompatibility horizon, of course, will be when Apple migrates the Mac as well off Intel chips and to their own in-house processors, as has been rumoured for a while now. Getting on the Intel architecture was what permitted so much of the PC/Mac synergy on the games side to begin with in the late 2000s and early 2010s, so you can bet on this as the final death blow.
It's not an environment developers can trust, and even as someone who prefers to play on the native Mac side, I wouldn't fault anyone for pulling out.
This is true. The whole lifespan of Mojave has acted as a transition period. The 32-bit cutoff mostly affects back catalogues, not new releases. The same goes for the Metal transition, which happened years ago.
The general issue, though, is a lack of trust in the stability of the release environment, when independent game projects can take years to roll out. And also the sense that Apple is continuing to shove macOS towards a black-boxed, mobile-like future. This affects a lot more niche development than just games.