Adding the option to "ban" keystones in banning phase

I think that adding a soft ban on keystones would be a really cool addition to the game, allowing for each team to essentially nerf a single keystone but still allow all 10 players the option to run that path. So my thought process is that team still gets their 5 bans but only one of those 5 can be used to 'ban' a keystone and once that has been used then the next 4 bans are champs or 'none'. I would imagine this being implemented as a reduction in numbers of that keystone so maybe ad/ap scaling gets reduced or the keystone gets reduced in numbers to being only 66% as effective as it normally would.

I think this would add a completely new depth to the game because you could still play all of the same team comps but power spikes would come at different times and it would create new opportunities in team play knowing that someone opted to take a champion with a 'nerfed' keystone. The keystone nerfs would obviously be applied to all players that ran that keystone, so in practice 2 keystone's at max would be nerfed for all 10 players and up to 10 champions would still be banned, giving no advantage to either team.

I would like to hear your thoughts on this and if you'd like to see it tested or why you think it wouldn't work.

edit: As Wolf ToddStar pointed out, this would do way more harm than good as some champions simply wouldn't work without a keystone and that makes the ban for more potent than a single champion ban.