Why don't we add Flash as an innate ability?

So had a pretty stupid idea while I was taking a nap, after a few losses and all ended up having nightmares playing League. But I digress, I had an idea that almost every single player uses Flash as their go to summoner spell, leaving viability up to only one different spell, very rarely or very specifically do you ever see someone take something over flash that wouldn't make them seem like a troll. So i thought, if we make flash an extra ability that has a different hotkey, don't even call it a summoner spell it'd just be a spell like that could look as small as the passive box for every champion, give it the same cooldown as it's original summoner spell (300 seconds), same mechanics land don't let it be affected by cooldown reduction i.e. volibear's ult, give it to every champion. That way every player has two open slots for summoner spells that allows for different combinations of viability, it would be a bit trickery to balance because supports could take both exhaust and ignite, midlaners could take teleport and ignite, etc. But if they're aiming for unique playstyles and interesting choices they (Riot) could make new summoner spells that allow for more variation. Nothing strong but allows for choices.

[slayer-pantheon-thumbs] Flash is the problem so just give it to everyone.