> it's clearly a dumb idea, why does everyone pretend it's not and engage in deep consideration of it?
I've learned that Trump is an incredibly dull instrument, but the points he raises (when you get past the verbal diarrhea) tend to be things that some significant fraction of his "base" care about or that are not actually novel policy ideas. "The wall" as he describes it is dumb. But it has existed in some form since the 1990s (albeit only segments) and the way he describes it is a simple symbol for people that tend not to know how to "solve" problems related to (illegal?) immigration.
Most average people don't care about policy details so they don't know how to argue them to "win the argument". Trump gives them a sports team to cheer for and simple slogans to shout so they feel like they are participating.
> when it is painfully obvious that the only reasoning by the president is "they messed with me so I'm going to get revenge".
The problems that Trump has with social media companies go back far more than 2 days and a fact checking link. His Attorney Generals (both Barr and Sessions) have been working with Republican state Attorneys General for years to craft a response to what they see is "liberal Silicon Valley techies banning (or shadowbanning or remonetizing or ...) conservative voices". Trump doesn't see a downside to taking this action.
The interesting thing is that there are far more than just political American conservatives that want to see regulation of {YouTube, Facebook, Twitter, etc}. Elizabeth Warren wrote a detailed essay on medium.com about why they should be more strictly regulated. A crazy YouTuber from San Diego got so pissed at YouTube for banning her account or demonetizing her channel that she drove up to San Bruno (not sure exactly which city/location) and shot up the building. There are quite a few stories of vague ToS being enforced in a not-so-predictable manner which leaves end users with banned accounts (which may be the nexus to more important accounts like email accounts).