Opinions of games engines

Hi guys, me again.

I got into a discussion with a friend of mine about the difficulties of getting into the games industry as a recent graduate, along the way our discussion moved on to questions regarding games engines and i admit its a question that has been hanging over me.

Construct 2, Game Maker, Unity these are some of the many games engines (non Java related) that exist and i am wondering why would people opt to not using them. Can the community point out the flaws of such engines to me and whether i should avoid them, do you think they are a cheaters way to make games (my actual opinion at this time)