Earlier quoted context omitted.
I would hope people just go back to writing engines from scratch. It's really not that hard and unlocks being able to do unique non cookie cutter things which in the end games are supposed to contain.
Writing your own engine requires a far stronger knowledge of math, rendering, audio, and networking (just to start with) than the median dev has, probably by a few orders of magnitude.
Rendering libraries like Monogame hit a sweet spot of shielding the developer from most of the complex rendering maths, while being general enough to allow you structure your code how you like. Simple rendering libraries are a much harder sell though because a capabilities video demonstrating rotating sprites and blend modes doesn’t seem as enticing as Quixel scanned environments or Dynamically globally illuminated assets.