Especially in the current voice application climate?
It's easier than ever to just throw in a discord link in the pre game lobby to have everybody join.
Most discord servers either don't care about "random" people joining their server (with at least someone in the server knowing the random)
Or their servers are properly managed, having different rights for every role, and a role for random people.
With random people I mean premade who are not actually part of the main friend group of that person, or someone they added and played with before.
However, most people don't really want actual randoms (the people you're matched with) to join their servers and wouldn't throw a discord link in a champ select with 4 people they don't know.
The whole point of voice chat is to be able to have you communicate with random people without any commitments or sharing personal info (discord name with linked steam/gamertag/whatever).
If I'm premade with anyone, I will have them in at least one of my discord servers, making the whole premade voice chat obsolete. And I think this counts for most people.
Also in this thread, hormones.
What are they and how do they work. Scroll down for more info