Mainly though it’s through the act of attempting implementation and interacting with the world that you learn the most. Someone who refuses to try to do this to get better probably just isn’t very capable and their ideas probably aren’t very good.
Even if you do come up with an idea that is viable most of the time so have others and it’s the successful execution that sets you apart.
I’ve met people that sit around patting themselves on the back for having the same idea that someone else used to actually build something.
While having the insight is critical, it’s a lot smaller part (also usually their idea was a vague generalization of whatever ended up existing).
Kind of reminds me of how the Winklevoss twins were portrayed in the social network, no idea how true to life that is - but that sense of ownership they had when they didn’t really do anything of value.
The idea might potentially be interesting in itself, but without the implementation it won't be all that useful.