Game mode

Simple question: Can we one day have a map editor?

If not, why ? If yes, how ? I see it as you can input any rules you wanna.

For example no tanking items, block some champions, no item limit, something like 50 % cdr for all players.

I was wondering if riot was not doing it for economical purposes or just because their don't wanna. Because it would be easy for them to do that a bit like the new training system.

Now honestly I think being able to edit your own mode in lol would be so much fun in my opinion, like you could do 10vs10 and even maybe edit your own map.

I never saw people talk about that. I was wondering if anyone had any thoughs on this matter, if yes I would be pleased to hear it. Also their is custom games so why not custom modes ?