Lethality Balancing

I'd just like to understand the logic and reasoning behind why Lethality is being balanced the way it is right now. In patch 7.2 the stat was adjusted to have a 60-40 ratio to make it relevant. We all know how that ended up.

However, I'm seeing that there's no adjustments being made to that 60-40 to see if a lower ratio is better. Maybe a lot of testing was done and 60-40 was the magic number? I don't know. But I find it odd that, on the surface, it seems the 60-40 is being really forced at the expense of everything else.

Namely champions such as ADC-, , , . These guys, from what I'm seeing on websites, were barely touched since early/mid S6 (barring Talon) and from the looks of it were pretty mediocre in terms of pick rate and winrate. That is, of course, until 7.2 hit. Now that the 60-40 is being "forced" for lethality, they are seeing the limelight. But instead of dialing down the source of the problem, the champions themselves are starting to see nerfs lined up for 7.5. They're tentative, I know, but I want to prove a point. is receiving a pretty big nerf where her 2nd Q bonus damage is completely removed. has a hefty nerf lined up as well. As far as I know, these champions don't have overloaded kits. They just abuse the stat heavily. It's unfair that they get punished for this. Why not nerf the stat? Why not put a cap? There are other work arounds.

TL;DR - I'm just confused to why the 60-40 is being avoided for now, and instead everyone else is being punished to compensate for that number to exist. It just seems more obviously logical to tackle the source of the problem in the first place, instead of beating around the bush. Lethality, IMO, does need more nerfs. So wouldn't that open up the possibility of over-nerfing when you tone down champions who were only strong because of said stat to begin with? Seems really convoluted to me. Then again, I could be completely wrong and it isn't exactly so cookie-cutter. This is just from my perspective at the moment.