The reason Blizzard allows premade BG groups is because Blizzard thinks we get too much for our monthly subscription - and 30 year old full price game?
The reason Blizzard allow premades is because the game is boring solo and the queues are long enough without there being two separate queues.
Entering battleground queues solo, with far from the best gear, was my end-game in WoW for some time during vanilla. It continued to be a major activity for years, even after I picked up raiding again.
From playing low level brackets - learning classes, to playing my main.
Would I, and so many others, have spent that much time doing that if 3/4 queues were premades? Hell no. There were premades back then too but they were rare and most people took it as a challenge to put up a good fight, maybe even win.
Now? Everyone sits in ghost, and I don’t blame these players entirely either.
There are things that we can maybe excuse the devs for not bothering with but this is not one of those. They just don’t care, and it shows.
I’m fairly certain if they implemented such a change a lot more players would queue battlegrounds, it makes no sense to ignore this reality for so long… unless it is on purpose.