Same thing applies to ppl who play custom 1v1 in global, same thing applies to crater players outside crater, seton players outside seton ect. We don't have spearated ratings for seton, for crater ect. BUT we separate ppl that are actually capable to play great variety of maps by themselves without any help.
There was a reason ladder was separated from global in past. It was done by ZeP and he mentioned main reason being ability to drop rating quickly through ladder. This was done by Just_a_game for example. Now tell me does this fix an issue? We banned 3 players last week who managed to drop more than 1k rating - that's the answer for you about how that change works.
Another point was to prevent ppl from being "overrated". You will get even more overrated if you play custom 1v1s. Clear example: SB_NEXUS, KvaGa, Malantrius - all farmed 1800 on Winter duel at some point. Did unrated ladder prevent them from being overrated?
we are actually trying to find a way to make different map or mod having their own rating. Listen to people talking about trueskill2. As i said, it's not because the rating sucks already that we need to make it sucks even more. People spamming custom 1v1, or only 1 map are fucking up the rating.
Now you pointed 3 guys fucking up the rating because they abused the fact that you can get high rating playing custom 1v1, and what you are asking for is too allow all people playing ladder to f*** up their global rating. That is just a non-sense.
When i was hosting custom 1v1, i did unrate on purpose the game i was playing so that it doesn't affect the "global rating", which i think we should rename "teamgame rating".