Makes sense if there’s one nation that dominates economically and/or diplomatically. Like English today, IRL.
Though, if one group does not have such a strong influence, you’d probably end up with something like the “Lingua Franca,” a mix of multiple languages spoken by the most relevant nations (IRL, in Renaissance Western Europe that was a mix of Italian, Greek, Arabic, Turkish, etc.)
So Common may not be a proper language at all, but instead be a creole/pidgin of all the other big ones. So characters hearing a language they do not speak might still catch words here and there allowing them to decipher the gist of what was said. Also, Common would most likely be spoken in more metropolitan areas. A backwoods farming town may only really speak their native tongue, save for the mayor or merchants.
I'd like to add the OGL they were pushing would have effectively allowed them to steal homebrew and 3rd party content. They'd reserve the right to resell this content as their own or make it disappear altogether.
This would include supplements and adventures, of course, but the way it was worded, it would even include blogs and YouTube videos, etc.
Of course this isn't a unique situation (Meta has done this forever, for example)