I mean honestly how many teams would benefit from a 7th player yelling instructions?
Yeah, implying one team that chooses a coach to maincall would pick a retard who knows nothing about the game. When you choose a coach to maincall, I guess every team is going to choose wisely, no way you wouldn't benefit from it.
Some teams have been formed and sometimes not a single player among those teams was a maincaller. In CS for instance, the brazilian team Tempo Storm (now Immortals) had no IGL, which is why boltz decided to take over the IGL duties in spite of having little experience in this domain, and he did great (zews is the IGL now, but boltz did lead for some time). Same goes for FalleN actually I believe, and he's the best IGL in the world.
I might be wrong here, but I even wonder if kaidus' first time maincalling wasn't with BFF in season 14, because until then he had been on teams with established maincallers (Zebbo in season 13 BFF I guess, probably Byte in TCM...) I did some research but can't confirm my claims so perhaps the man himself if he reads me can tell if I'm in the right or not.
Kaidus might have built something with Crowns before he had to retire, but when your maincaller leaves, either pick a player to replace him who has maincalling abilities, or have one of your current players become the maincaller. It's not impossible, it takes work, and a lot of dedication (and a bit of talent), but that's how it should be, that's another component of the skills you have to possess to play TF2 at this level. And you can't just rely on an external person to do this work for you. Like fuck, Epsilon had numlocked and KnoxXx, literally both of them were maincallers, don't go telling me not a single Crowns player has the gamesense and knowledge to actually maincall, to pick up from what Kaidus left behind him.
Maincallers aren't born, they're made, that's why in my opinion coaches shouldn't be allowed to maincall. However I have nothing against coaches if they do their work outside of the game.