You are spot on. After checking some recommended sites here (e.g. /r/appideas) it's clear that a lot of people just shitting out (for lack of a better word) ideas without half of a thought on execution. I think there are a particular kind of people who do this. The kind who wants to patent everything and always looking for the Next Big Thing™.
I have no solution for this other then focusing on the following things:
- How detailed the idea is. The mere fact that someone took the time to think about it and write it down (1-2 page at least) is a good first filter that throws out things such as "It's like tinder but for job search".
- Limiting it to "technical" people who has experience with actual execution of ideas and instinctively point out problems
Being successful at business is a different skillset than having good technical ideas. The best idea in the world won't build you a sales force magically nor will it put into place a manufacturing chain for you.
But if you can consistently predict whether an idea is "good", by definition you should be either hitting it out of the park consistently or getting massive returns on investments.
If you want a repository for good ideas, I think first you need to find a way to filter the bad ones.