I used to have 5 accounts, 4 of them simultaneous global around 2016-17.
All the accounts had to be grinded to global and I got fed up playing in global since the challenge isn't really that much bigger but there is absolutely no reward in winning a game in global. You can't rank up, only down. That's why I ended up playing several accounts to global. You can't reach GE immediately and in cases of some of the accounts, they're owned by a friend of mine..
He started CSGO when the 2 match wins/day bs came. He played 2 wins and bought a new account to continue playing afterwards.
And by my experience, there's a shitton of smurfs likewise to my experience. Some try to grind ELO to sell accounts, others just do it because GE is boring and some are afraid of losing their MM rank on their main especially if they play with lower skilled IRLs and then there are the boosters..