OpenBSD went through a similar transition, except they didn't even try to maintain ABI compatibility. See https://www.openbsd.org/55.html and https://www.openbsd.org/faq/upgrade55.html, the latter describing the rare "flag day" event. Long term this was good for OpenBSD as it saved a ton of unnecessary cruft and complexity that would have haunted OpenBSD for years if not decades, endlessly taxing developers' time, especially of core developers. And it was an inducement for all developers, those working on OpenBSD (core and ports teams) as well as those targeting OpenBSD, to carefully review code for 64-bit time_t safety. But it necessarily required that the broader community shoulder a large part of the transition burden.

Sometimes it's better to power through with a massive labor effort than to try to use fancy hacks to shield people from latent problems. All things considered, it doesn't sound like the Alpine transition was that bad. But it's the type of thing that most Linux users and developers are not accustomed to, at least those who don't remember the very early years. Ironically, musl libc might not exist if glibc hadn't accumulated so much complexity trying to maintain strong ABI compatibility.

IMO, small prices to pay for free software and Free Software.