[2022] Why does riot not push linear itemisation on champions if the majority of players just play the same item every game?

I feel like riot keeps making more and more balance nightmares, be it new champs or old champs with new builds. There's not much honestly to incentivise certain champs to stick with their build. For example, tank diana was the most recent example of a problematic build as a result of diana not being forced in AP itemisation, similarly we have had stuff like Tank Akali, Goredrinker assassins and other stuff that people generally found annoying. I feel like this is a reccuring problem that could easily be fixed with adding more scalings to a champs kit.

For example, pyke is forced into building lethality effectively, a lot of his ratios are based on ad and lethality meaning he can only really stick to his assassin items. For a support assassin seeming like a really hard thing to balance, pyke is honestly not that bad unless he's played mid (which they have taken precautions to stop by simply adding more variables to his kit to make balancing him even easier). Ornn is another example, he can itemise flexibly within the bounds of Tank itemisation. His ratios are pretty small on his abilities so you don't catch things like AP or AD ornn, he gets bonuses for building Tank both damage wise and just bonus stats in general, so he is effectively confined to building Tank and can be balanced around that accordingly. Rell is another case where a champion has such low ratios as a tank and bonuses from building armour and HP that there's no point going AP realistically, avoiding the problem all together.

That's when I realised that they should simply add more ratios to character kits. For example, talon could get a negative hit to his AD ratios, but supplemented by adding lethality ratios. This would nerf the bruiser option which violates the rules of being an assassin and forces him to play as an assassin who has high risk and high reward. If bruiser items are too strong still, nerf AD and buff lethality, rather than buffing base stats or alternate fixes. Each role could have one universal stat that defines the role, such as lethality for assassins, crit for adc, mana for mages, etc. Champs that have issues with alternate builds, such as fizz building a mage mythic, can simply be adjusted accordingly.

While I feel like it might be a lot of initial effort, I feel like it would result in a more healthy balance for the game plus it would give the balance team more options towards tackling balance problems. Although this will probably never happen seeing as it's a pretty huge overall, what are peoples thoughts on this?