> free speech meant the freedom to speak your mind
As long as you were white, reasonably well-off, and probably male, yes. It did not mean that for almost everyone else.
Also "speaking your mind" has never been (and never should be) consequence free. There was just no recourse for the majority to apply consequences until recently.
> The idea that people would routinely get fired for voicing their opinions [...] would have seemed shockingly unfree.
I'm pretty sure people have been fired for voicing their opinions all the time - it just wasn't white folk, especially men. And not just fired - plenty of people have been killed for voicing their opinion in the USA since day 1. Just not really white folk, especially men.
> That's where society used to draw the limit.
Because society used to be a lot more lopsided in terms of diversity, power balance, etc. Now the balance has shifted and some of the people who previously had all the power do not like it one bit.