> Really I have no idea what this case accomplished besides being a tax on a successful company.

You forgot "evil" in your description of the company.

It is supposed to realign their incentives away from massively exploiting society for purely financial gain. There is ample evidence that Meta has gone out of its way to encourage the discussed issues, so clearly there was a problem with the incentive structure. Given all the lobbying they've done to prevent any passage of laws regulating their conduct, it's fallen to the courts to correct this (if, as other comments say, somewhat unsatisfactorily).