Thank you for your well thought out and presented reply; I greatly enjoy such exchanges and think any reading Devs do too.
As I indicated, modding and rolling back are extreme options - if it comes to it - as in, if a player cannot wait for the update which will, doubtlessly, tweak them. The other options come first - but it is far more useful feedback for a player to be saying 'I made this mod / change and here is my experience' than 'I'm not engaging with this at all - change it'.
Equally it is far better for a player to go 'on X difficulty, at X gamestage and with X alive at a time this proved beyond me, but when I turned it down to X it was manageable; as that helps zero in on where the Demolisher ought to sit. All of the tweakable settinjgs are there ingame for this exact reason; so that is something is proving beyond you, you can change settings to find a level at which is it manageable and feed that back.
I recommend settings and practise for those who are saying they want to engage and find strategies which deal with Demos; but I recommend mods or rollbacks to the players who are saying 'this is stupid and I don't want to deal with it'.
Yes, people are saying they are fundamentally broken and, to quote the OP 'stupid'. This is not the only person making such claims, but the majority of those people are also demonstrating a failure to read, explore, adapt and accept that the new challenges are challenging.
I have to disagree with you - none of the traps are obsolete now, nothing is 'off the table' - you just have to use them differently. Watching Kage848 - who is not a GREAT player - shows all of these things being used and it only fell apart when he made mistakes. It is entirely correct that making mistakes should cause you problems. Had his intended strategy of using M60 with AP ammo been performed without his mistakes he would have had no problems at all. I am not a GREAT player, and I am managing with a similar strategy and having some success with others. The problem is that you can't use pre alpha 18 strategies the same way anymore; and it is a player mistake to do so.
The only limited choices I have seen is from players saying 'I want to build a specific base and use specific weapons and a specific strategy (usually one from alpha <16) and want it to work like it used to. That is their choice to limit their playstyle.
Once again, you specify ONE option for working around demolishers - ignoring 'know what enemies are in your game, know when and where you are likely to encounter them, know what sorts of defences, weapons and strategies are good against them and which are not'.
It's a fairly well known and established trope of games where the threat increases as you level up to be picky about how and when you do so - from Final Fantasy to Fallout, from Hogs of War and Cannon Fodder to any number of games which one could name. I would agree that the documentation and ingame tutorials could make this information clearer - but 7 days to die has NEVER been kind to blind play; from alpha 1 to 18. But such a loud and big deal has been made of the demolishers that anyone who isn't aware of them must be trying pretty hard to not do any prep.