An oversimplification doesn't mean you get to make completely false statements. An oversimplification ignores other significant factors to end up with a simple statement that for the most part is true.

It's rare because we have higher hygiene standards

This is an acceptable oversimplification.

Basically washing our hands eliminated the black plague.

This is not because this is just factually wrong.

The latter is what is being corrected. Now apply your smartass education and understand when you're wrong.

In an era of anti-vax bullshit, it's not acceptable to be that incorrect in your "oversimplification".

I understand what “oversimplification” means. You do not seem to understand what “incorrect“ means.