Because they don't care about individuals. They get their money from you by selling data and making you comfortable in an environment so when you get into corporations, you choose Windows.
Same reason Adobe doesn't really care if you pirate CC suite, when you need to use something professionally they are banking on you requesting the businesses buy their products
Your IT team is doing it wrong then. You can map SharePoint sites directly to file explorer. Now that brings on a whole different set of issues ala OneDrive, which IMO is an even steamier pile of shit, but still - it's better than going straight through Teams