Who said anything about convincing people? I'm explaining why it's a challenge to consider a position that may be more valid now, but wasn't valid or was substantially less valid in the past.

It was an abjectly stupid position, held by stupid people. Now, it's possible that the situation has changed and it's marginally less stupid of a position, or even not a stupid position at all, given new information.

It's hard for people to make that switch.