[joseda-hg]

You're pretty much on point, unless you're making something really specific/that needs every bit of performance that it can get, you're better served by an existing engine

A good example of something that was better served by inhouse engine is Factorio, but that' uncommon

[seba_dos1]

Another case is doing something technologically simple enough that benefits from having a fully customized workflow outweigh having to write some stuff by yourself. This can happen with content-heavy genres like, say, 2D point'n'clicks - you don't get much by using an existing engine there, but you have to follow its idiosyncrasies which may or may not work well for you and your team.