Admittedly, one piece of input reading this thread I want to give, is that 5e's failures of execution aren't failures of structure or taxonomy.
So for instance, 5e might have trouble making player characters feel like they're in danger, not because it needs to be a narrower system, but because the encounter building rules can't build 'actually difficult' encounters for reasonably optimized PCs, which was either a decision or a mistake the designers made somewhere along the way.
I've had near TPKs at every level and, no, I don't use any house rules to make things more difficult. I don't have to hack the game to change the difficulty, the DM has infinite dragons. The only optional rule I use is the alternate rest rules, but that's as much for pacing as anything. Not that I need infinite dragons, 3 frost worms (CR 17) against a 19th level party almost did a couple PCs in because I took advantage of their abilities.
When a GM hacks 5e and makes these things work, they're demonstrating that a version of 5e that had those rules in the book, or that had been designed a bit differently up front would have been able to handle that fine without becoming a more focused game. This can apply to all sorts of things, 5e isn't good for crafting and downtime? Well it sure would have been if they'd set it up to be, 5e isn't good at intrigue and politics? Well, it sure would be if we had a good subsystem for tracking it pre-installed.
As far as a subsystem for intrigue and politics I guess I never wanted one because when you do that it just becomes a mini game. It feels less immersive to me and too predictable if I have "influence points" if it's player facing. If it's not player facing all I have to do as a DM is think about the individuals or organizations involved and how they'd likely react. If I felt I needed such a system, 3PP is right there to fill in the gaps.
It's fine if you want a system that gamifies aspects that D&D doesn't, it doesn't mean I feel like I'm missing anything.