'Stealing' an idea is almost meaningless in this context. Everything is a copy of everything else on some level.
It's called competition. If one person makes a game/app/whatever, and does a poor job of it (regardless of the reason, be it inexperience, lack of motivation, whatever), and someone else takes the idea and provides a much better implementation, why is that such an issue?
I know I wouldn't like it if someone took my idea like that but I would just have to deal with it. Someone else did a better job than I did, that's my problem, not theirs.
Just my humble opinion.