I suspect that if someone is in a position where they are compelled to purchase and use the proprietary version and not the free (and available) version, they already lack most software freedoms. Probably several other, more important, freedoms as well.
Although I agree, notice that the only act the GPL compels someone to do is to hand over the source code with the program.
MIT doesn't give people a freedom to restrict because that isn't a freedom. The restriction is always done by the legal system. The GPL is just an attempt to stop the legal system from interfering in the market to restrict user freedom. So both licenses are actually communicating to a 3rd party (a judge) under what circumstances they should restrict the freedom of others. GPL says to stay out of it as long as people are sharing their source code and MIT says get involved sometimes/its complicated.
It isn't a practical difference, but it is philosophically important. The amount of personal freedom both licenses give is technically quite similar.
MIT doesn’t give anyone the ability to restrict the freedom of others. When you fork a project and use a difference licence for it, the original project remains under MIT.