It has some "rivalry" effects ;-) .
When CertainlyT bypasses the testing & balance team by making complex calculations, he made some champions borderline OP (i.e. oppressive when you know how to exploit the kit - make it much more damage than how it looks first).
He came up with some nice innovations - how to make OP champs without being nerfed severely by balance team? Big numbers are not likely to pass, so what did he do?
Opponents has dash and blink? Ok now I'll give my champ Mulptiple dash/blinks (to a point it's like infinite).
Another way is to inject some hidden stats via "passive", CertainlyT did it well.
Yet another way is stacking damage, the classical way is via AoE damage, the new way is stacking ability or stacking points: if you hit a Q then you can hit another Q; or stack multi points Q to proc consumption as a burst.
He also combines some nice ideas like "extra dash" (Thresh lantern), or "slow box" (Karthus+Veigar = Thresh's ult); or comebine untargetability to dash/pet would increase outplay ability to next level. Don't have to be 'ultimate' skill as low CD, it's good if that skill can be spammed.
That's the reason why when other designers starts to realize those, they also wants their designed champion has some "nice" damage. Which leads to the points of "true damage" as you see.
Example:
- Tom Kent has hidden stats like "sustain+shield" (for defense), and +8% health as damage (for attack). If this trend continues, many old champions have to be re-worked cause their old kits can not compete - their numbers are reduced already and some buffs would not exist past a few months because their is no "smart way" to hide that from testers.
- Ekko also has some hidden stats but it's more obvious so the numbers are toned down a bit. Some later designed champs (like Juggernauts) were disguised smarter to avoid nerfs not soon as Ekko - for example, some %HP dmg ;-) .