For me, it has to do with deathmatch queue.

Say I want to play Deathmatch. I don’t ever really even want to play the “proper” Deathmatch gamemode (because it sucks), I just want to DM endlessly. Essentially I want to play the waiting Deathmatch forever. Can I queue for that? No. Fortunately, I live in OCE, which means I can hardly ever even find a match in Deathmatch. So, I’ll queue Deathmatch, and then while waiting for a match I’ll load into some Deathmatch. Makes sense so far, no problems right? Except, a lot of the time I’ll load into an empty Deathmatch server. Is this because there’s not enough players playing Deathmatch? You might think so, but no. Because I can queue some Unranked, hop into the “While you wait” Deathmatch, and get put in a lobby full of people.

Simply put, my assumption is that the waiting lobby deathmatch queues are split for different gamemodes, making it literally impossible to just play deatmatch in OCE at certain times, despite there being plenty of people PLAYING deathmatch at that moment.