The law has absolutely nothing to do with historic content, it has no provisions for or relevance to content published decades ago. Even in the most cautious response to this law, there is no reason to take content offline.
Let's be real, for most dead sites this is an excuse for old admins to close the thing down because they got tired of running it. For sites with fewer than millions of users you basically needed to add a contact form and report button. These places are just deserted, and instead of having a few angry oldheads screaming at you, you can just blame the government
I think it's equally likely that people didn't take them seriously, but each new law has had increasingly dire consequences AND has been increasingly difficult to decipher. So there's that.