Again, I’ve never had this issue and never has anyone I know. They don’t call companies to ask if you were fired. They ask and tell you if you worked there and for what dates.
"Except you know that won't work if in fact they do ask you question X, right?"
"Doesn't matter, because they they won't ask you anyway."
Weird.
In any case it absolutely is standard practice for a significant portion of companies to go this route (especially in more traditional sectors). Even if it hasn't happened to you personally, or to people in your bubble world.
This is HN - the bubble of Silicon Valley and venture capital. I can tell you with great certainty it is incredibly uncommon to encounter people in HR who will tell you the reason why X person left the company. In a region that is happy to do lawsuits - they don't bother. After all - it's no longer their issue. They'll just verify dates of employment and that's it.
Reason for leaving is never told.