I’ve not run up against this problem personally, but we’ve all seen the regressives’ attempts to hijack the holidays:

The Left’s Unending Fascination With Scripts to Browbeat Relatives on Thanksgiving Strongly Resemble… Scripts for Religious Conversion

Supposedly progressives are super-informed and Love Science. Indeed, that’s the main “political” argument they’re actually arguing for.

So why is it so many of them seem to need these bluffer’s guides to explain to them why they believe the things they believe?

It doesn’t really make sense, does it? They’re anxious because they’re going to a Thanksgiving dinner where they won’t have an Automatic Affirmation Clap Circle applauding their poses and posturings, but instead might be asked things like “Where are you getting that claim from?”