To any Rioter willing to comment: Adaptive

Adaptive has been a wonderful addition to the game, imo. It allows multiple people to take the same rune, but benefit from it differently!

However, there is one place that seems perfect for Adaptive, but does not seem to have it (unless I've missed it) ... Champions!

Adaptive seems like an awesome way to allow different builds to passively affect champions play-style and abilities during the game.

Let's use the upcoming changes to Rengar as an example: With the addition of the AP ratio on Bola Strike, it is apparent that Riot is accepting the AP Rengar build-path and play-style. However, now it has both an AD and AP ratio on the ability. We all know how abilities with multiple ratios can sometimes feel... cough cough ... annoying to deal with.
However, this doesn't have to be the case! What if adaptive was added onto champ abilities, or even passives! Imagine the ability decided what ratio to use based on the current AD or AP stat?

Imagine how many alternative builds could open up for other champions! Obviously not all could happen this way, but it could be a blessing for some.

Another Rengar related example is his updated R. It, tentatively, shreds Armor if you jump to the closest target (instead of critting). What if it decided to shred Armor or MR based on Adaptive?

TL:DR - I think "adaptive" should be implemented into some champion kits to allow abilities or alternative builds to flourish without being overbearing.

Main Rioter questions: Why isn't this already a thing? Has it been brought up before? If so, what made it not be included?

Thanks!