Old Macs can certainly be downgraded. iOS doesn’t allow it though and they pulled the latest security update which fucking sucks. And if you buy a M5, Tahoe is the only OS that’s available.
>If you buy a machine that isn't even released yet
Uhh, I guess.
AFAIK iOS has been very locked down wrt rolling back upgrades since forever and isn't super relevant to this thread. Happy to be corrected.
I have nothing against old Macs and MacOS, but I certainly won't be buying anything since the Apple Silicon switch, because now only Apple controls which OS you can run.