The developers don't want to maintain old clients...backward compatibility proved too expensive. Apple proved autoupdate is the way. Browser vendors did the same.
I don't think people expect old clients to be maintained, but I generally don't like auto-updating. I don't want my computer to use CPU, disk I/O, or network bandwidth for updates except when it's convenient for me. Also, in some cases it can be worth it to stick with an older version if a newer version introduces a bug or something.
Me too. I'm going to avoid snaps now that I know this.
My OSX auto uptate is disabled. I'm still using Yosemite. It asks nicely occasionally if/when I want to upgrade. It does not install updates in an annoying way lke Windows does.
But at the very least, Apple lets users disable automatic update (and always have, always will). The default is automatic updates, but it's far from forced.