Not only that but there are decisionmakers in organizations that also use free tiers for stuff in their private lives. Piss one of them off enough and suddenly you can lose a big sale or existing customer.

So tinkering with free plans downwards can have unforeseen consequences.

And with the amount of data slack uses so low and costs of bandwidth and spinning rust approaching zero - the idea that free tier limitation are anything other than create a painpoint for people to upgrade is a joke.