SolarLightSpe0as you can discern from the above graph (even if it is a bit outdated) the absolute majority of tf2 players are found in gamemodes not included in the base game
This is actually very enlightening and explains a lot. Thanks. Might be something I can point out...
Edit: These are community servers only, right?
you're right, i somehow missed the title that clearly states its community servers only so i decided look more into it.
The graph comes from this reddit thread.
and the following is a distribution of players in Casual only
https://i.imgur.com/jaKjkyA.png
while its not as bleak as my previous comment suggests, the picture painted here isn't very rosy either.
after some very rough maths, i found that a whopping 36% of total players(Community + Casual) are playing the base gamemodes not counting ctf because why would we considering we all know its mostly people dicking around in 2fort and turbine, and this is factoring in a/d and plr which again as we know is mostly people dicking around in dustbowl and hightower.
but then again, these stats are from 2017 so things might be quite different now.
One interesting thing i noticed was that the amount of players in community servers was higher than in valve servers (max of 20k vs 17k) which might not be the case anymore.
teamwork.tf actually posted stats for march of 2017 here which doesn't really look all that different from the jan one but i wonder if they were able to post some newer ones just to see if things are still the same.
Overall I think my point about the general casual tf2 playerbase treating the game as Gmod-Free version is quite accurate