I feel like I am reading a post that was made 8 years ago when dungeons were still relevant.
In the past couple of months since I returned to the game, I have not been booted once from a party/squad for playing engi. However, I admit it's true that the expectation is that if you're playing engi you're specced with holo, which is unfortunate--I do miss when condi core engi still offered competitive dmg in PvE.
I disagree that playing engi requires "perfect keyboard piano" play. From the perspective of someone who was pretty hardcore with power/condi core engi back when it was relevant, playing holo in PvE has noticeably lower skill floor and less micromanaging.
I've mained engi for 7 of the almost 9 years I've played GW2, and I would argue that engi is currently in a good spot regarding all game modes. As far as I am aware, we're meta in WvW and PvP, and while we may be off-meta in PvE there really isn't a significant gap in dmg in real settings. We still offer great dmg, great burst, excellent CC, and some of the most reliable vuln stacking in the game. Honestly, anyone not accepting a competently played engi in PvE (barring record runs) is just an idiot who probably has never even touched the class.