The ignorance of politicians
As the ongoing UK Cabinet reshuffle demonstrates yet again, complex and important departments in the running of a nation-state will be managed by people with no relevant experience, knowledge, expertise or qualifications. Any company that tried to operate this way would be bankrupt even before its shareholders could fire the entire board. If you wonder why policy and strategy are always such a mess, just look at the insane way Britain appoints ministers. Bad enough that they are mostly second-rate intellects, but they rarely have any worthwhile expertise for the job in hand.
May showed no comprehension of the profound reasons why the 'government back-door' approach simply cannot work, and politicians generally seem simply incapable of understanding that the way encryption works makes their statements and policies look plain stupid. I'd like to think someone would spend a couple of days going through the math and logic with these idiots, but they often seem to relish their cluelessness. Like the US Congress, they actually prefer to look and sound stupid.
As presumably everyone here knows, banning e2e encryption—even if workable, which I seriously doubt—simply guarantees a mushrooming of software comms tools with good crypto. And my guess is there will be a renewed interest in steganography, too.
Let us be clear: the only people this hurts are the ordinary users. The bad guys have a zillion alternatives, which they will use.