More importantly for better than or worse it’s just not how game lifecycles and financing go.
It isn't necessarily about API level, it could be (from time to time) about going from arm32 to arm64, to adding better-optimized builds for new microarchitectures, getting bitcode that's recompiled by Apple to support app thinning. Apple may deprecate or remove APIs from time to time that should also be addressed.
That there wasn't necessarily, specifically, a change this time doesn't mean that this program isn't about supporting that over time. It's much easier to make such changes if developers are in the habit of periodically making updates vs. being told to make a breaking update out of the blue.
And before you quote the number of “registered developers”, all of those aren’t paying developers.
Not sure what category of software that was but e.g. for games it’s usually not an issue. I used to have a bunch of games and game-adjacent software from the first AppStore year, we’re talking the time when you’d pay a buck for a virtual rain stick which’s use the accelerometer.
They kept working until the 64b switch killed them. Rebuilding them would undoubtedly have been difficult for the author even if they’d not moved away from them, but because those’d use only minimal is features (raw-ish inputs, and setting up opengl) there’s basically nothing to break which would not be flagrant.