One reason that I support alternative (non-Apple) app stores, is that it allows differentiation between mediocre and higher-Quality apps.
You can get your clothes from Target or Saks Fifth Avenue. For most folks, Target is fine, but there are people that insist on paying $30 for every pair of skivvies. I think that they should have that choice. If they can afford it, then let them eat cake (for the record, I tend to be a Costco type of guy, but have not regretted occasionally getting something from Saks).
Selfishly, I would like them to allow sideloads, because the App Store approval process has slowed to a crawl, lately, as well as APNS calls. I’m certain that’s because of thousands of AI-generated submissions. I think many of those submitters would much rather avoid the hoops they need to jump through, for the store.
But I doubt that Apple sees things that way. The secondary app stores are likely to make a lot of money, which they would miss.
The more damaging thing, however, is that Apple’s brand image could get corroded, and there’s a very good chance that they could be strongarmed into supporting side-loaded crapplets. I’m a bit cynical on this, myself. I feel that Apple has been doing a great job of damaging their own brand, in the past few years. I feel as if the quality of their internal engineering has declined precipitously.