Honestly, this post is a mess of assumptions, many typical. A couple of points:
Teams make games, esp. big titles, not devs. Teams include devs, artists, designers, and even external domain experts.
Teams brainstorm all the freaking time. Ideas come fast and fluid in a boiling pot like that.
Your idea is just that. Many ideas come and go, but may not be easily implementable or may not be sellable to a wide audience. Lots of time ideas that excite you will fall flat at large.
Because you have played lots of games doesn't mean you are a good designer. It's a necessary ingredient, but not the only one.
If you have an idea and no "pedigree" in the industry, your *only* real option is to start it out yourself. Your options include:
a) find money and fund it yourself
prototype/mod it on some existing game with "game creator" built in (prototypes don't have to be perfect) and then get with a publisher or build a team
c) prototype/mod it in something like Blender/Unity and then get with a publisher or build a team
d) find an indie team that you can help with their current project, get on their good side over time, then suggest your idea once you have their trust
e) work as a tester in a large studio, network and make connections, and eventually start a team on the side with colleagues
f) work in a smaller studio as a tester/QA, move into doing design as fast as you can (ask to help with documentation!) and get your idea in play once senior.
Those are some of your options.