At-will employment doesn't mean employers can fire employees for any reason, as some posters mentioned earlier.For the most part, it actually does. The only exception is that you can't fire employees for a "bad" reason (race, religion, etc.) That aside, you can fire them for any other reason, including no reason at all.
I'm all in favor of changing this so that employees can only be fired for "good" reasons (bad performance, theft, etc.) This would address the concern of the free speech bros without getting into snovvflake territory.
We’ve seen how much that has benefited the youth in France. You run into the problem of it being so hard to prove that it’s a good reason, like poor performance, that it becomes impossible to fire unproductive employees, making employers less likely to take a chance on someone with little work history.