The question is, why is it still like that? There are ways to unify scripts and their flow of information without huge amounts of performance being needed. Sure, you always need ways for exceptions in the end but even they should be able to get the flow of information inside that system.
The thing is that you (Riot) have a total mess and don't want to clean it up because it is a large mess. It requires a ton of work and likely won't make you any money. But it would increase the quality and shorten pipe lengths for many processes.
Now the longer you wait the larger that pile becomes and the worse the cleaning up will become. Now league has a life span so maybe the time never comes, but if Riots goal is to make league run for 10 more years, that mess, sooner or later, will just eat a ton of work due to bugs. I mean, league is known for being THE bug game due to a lot of the messy scripting.
So it is wrong to expect Riot to work on such a project? No, because it makes a ton of sense as the work has to be done sooner or later and the sooner the easier. Now when such work is done, it should become decently easy to implement such a feature as tracking conquerors bonus dmg.
Now I am not Riot and I can't tell you or Riot what you should be doing. But I am sure there are others at Riot that know this pretty well. Maybe many think league won't last for 10 more years and so Riot can just sit it out. I am not sure. But I know that this work should be done as I do exactly this.