I'm not one that's just havin a pop at Sony, but if the usual happens where Sony takes more stick than other companies, and it leads to the end of this bullshit, good.
Companies requiring multiple log ins are fluffing their numbers. Using the examples in your post is disingenuous as epic own Fortnite, battle net is diablo etc.
Now, what's bullshit is signing in with Xbox live/PSN and then having to sign in to battle.net (I won't do it). Signing in to multiple accounts is many people putting their hands into their pot to double the user numbers and mau. 1 Xbox user playing diablo + 1 battle.net user playing diablo = 2 mau on 1 account.
In this example, Sony have introduced this sign in requirement after the game has shopped, which is a bit shitty, which is what is pissing people off. Coming off of the back of the stellar blade rug pull doesn't look good.