https://store.steampowered.com/stats/

Sorted by active users:

    860,000 - CS:GO
    480,000 - DOTA 2
    173,000 - Source SDK Base 2013 Multiplayer (Mostly a multiplayer GTA mod)
    146,000 - Apex: Legends
    130,000 - PubG
    112,000 - Rust
    93,500 - Destiny 2
    88,400 - GTA V
    76,000 - Rocket League
    67,000 - R6:S
    62,000 - Football Manager

I think it's pretty clear that competitive multiplayer games are the gaming zeitgeist (On the PC). Rust, Destiny 2, GTA V + mod, and Football Manager are the only titles in this list that are really played in a non-competitive manner.

Now, its true that in terms of copies sold, competitive multiplayer games are not quite as dominant.

Yeah I'd say it's been the PC gaming zeitgeist for a long time now. That's fair.

Fortnite as of 6 months ago had 25 million daily active players.

Fortnite isn't really comparable to the list of top Steam games in my replies though.

Like Brawl Stars is also super popular, but it isn't exactly a "competitive multiplayer game" like dota. Most people play it casually without a huge care of W/L.