Honestly, you can make a horribly inefficient game using any engine. Unity just has a lower barrier to entry, as it's very hobbyist-friendly (as you rightly point out), so there's more games being made overall with it, more games made by people with little experience in performance optimization.

I don't see this as a bad thing, either. The tradeoff, from the hobbyist's point of view, is that if you decide to use Unreal Engine, for example, your cost of learning the tech is so high you're unlikely to ever finish your game.

Source: I'm a (professional) game developer and we've used Unity for multiple projects.