no one uses in game voice chat, literally no one. even the friendliest most inclusive games with really amazing voice chat systems(all 3 needed to belong to this list) like overwatch had players use voice chat for maybe 3 weeks after launch and then go back to their private discords.
In game voice chat is pretty common on CS:GO. Trying to get you group of 4 random teammates to hop on a specific discord is an annoying step.
I play Overwatch and CS:GO and in competitive matches it is the norm to use in-game voice, if you don't - you'll get flamed about it.