And Microsoft would likely be a smaller company had they not left it open.
Had Apple forced users to use Mac only to use iPod, it's likely Mac marketshare would skyrocket.
Anecdotal. I was ready to give Mac a shot if Apple forced users to use Mac to sync with the iPod. What you or I experienced isn't really saying much.
Again, Apple could likely grow the Mac marketshare much faster if they left it Mac exclusive, meanwhile Microsoft would be much weaker if Microsoft closed off Windows.
There is a lot of parallel between this and how Tesla had exclusive Supercharger access. People simply wouldn't buy an EV that isn't a Tesla because the didn't have access to the charging network. Now that Tesla is opening up their Superchargers, you see a lot of interest in other EVs like Rivian and Ford and Tesla is showing weakness in Model Y demand currently.