A lot of inexperienced amateurish devs seem to think that making games in an advanced modern engine will result them into amazing games. In truth, they let their ambition get the best of them. They tend to lack experience and often start with the bigger things, rather than ease themselves into the program and make small, simple games first to gradually build themselves up. That's why a lot of their games turned out to be so terrible.

Not to mention, free-roaming games may seem to be the future, but it's not easy to make it good or fun given to what you said. Scott said is best that limitations will often net in the best ideas. This resulted in FNaF. In fact, even in the old games from 20 to 30 years ago, devs are forced to work within the limitations they have and achieved a lot of amazing stuff. I've seen this with games on Atari 2600 for pete's sake, where the hardware is meant to run games like Pong with two or three sprites on the screen, yet devs managed to have more than run! The Space Invaders port had 32 sprites run at once, but that would be impossible given to the hardware limitations I mentioned earlier.

I'm not knocking on Unity as it's a very good program for making 3D games and I've seen people make a ton of amazing stuff with it, but below level amateurs often abuse whatever program they have and make shoddy games. I've seen this with FNaF SFM animations that made the program look bad and even as far as MS Paint! No really, someone made THIS with MS Paint. It's about the experience they have, not the program, and the former is the deciding factor for the product.