Not sure how I didn't see this thread, but figured I should comment on things people can do to help this issue that is consistently talked about yet neglected due to. . well multiple facets.
First off as Ire said I do the main Liquipedia editing now for TF2 (although its slowed down recently but I digress), and there are multiple issues about writing things from just "word of mouth" that you just hear through Mumble. Although I highly encourage the discussion of the history of this game, simply saying "I heard it from someone" isn't really enough to add it to something like Liquipedia. Just like on Wikipedia, there needs to be sources. Wikipedia is a collection of sources explaining a subject, just like how Liquipedia is a collection of sources to explain a tournament, a players history, a teams history etc. As of this moment there aren't that many "sources" we can use to officially document some of these amazing stories, ALTHOUGH there are things people can do - such as interviews. Not just written (shoutout to all the guys who write articles) but video interviews with players, staff, admins, or anyone who can chime in on the incredibly in-depth history about the scene. I beg, BEG, for someone to put in the effort to interview people who are willing to tell stories about anything revolving TF2, and make it public.
The reason these other esports titles are so big is because we see content 24/7. Articles, Interviews, Critical Journalism, pre game interviews, after game interviews, how many CSGO and LoL interviews do you see daily? Its an insane amount of content. "Oh but Moixxoi we don't have the player base, we don't have the resources". Shut up, there are games with similar player bases that put just as much effort in, and maintain a flourishing historical archive of their scene through all the outlets I just listed. Warcraft3 has less overall players (estimated at 1800 current players), zero support from their dev, and a community made client everything competitive is ran through - sound familiar? Yet there are interviews done in Chinese, French, Spanish, German, English, Korean, by multiple different communities to try and preserve their history. I personally used to cast Korean Challengers (tier 2 Korean LoL) for the sake of preservation, I wasn't a good caster but so what, it was something for people to look back on and remember. You can your friend remember a player who was dogshit in Main and then rose up into Invite? Record a little talk between you two, discussing how said ex teammate used to play, interact, anything, it all helps to try and grow a narrative. And for Liquipedias sake it gives us something to reference so we can write it down as "official".
I feel like I could go on and on about this, but I've been a part of so many different scenes, and seen this issue happen before, yet it was solved by people putting in the effort. I wish I could do it all myself, but I am not a TF2 expert by any means nor claim to be one. There are games, scenes, and communities I have been a part of where there isn't even a sliver of support compared to what you guys have, so try and do something while there are still people around to talk about it all. I haven't even been around that long, yet I am absolutely elated whenever someone goes on a prolix explanation of a player who isn't around anymore (or even still is active).
If you want me to talk about this subject more (which is unlikely), I'll continue to do so, but I don't feel like a wall of text is the most inviting thing when it comes to these topics.
I also want to say that data, and match results are pretty much the least of our worries, almost all of that information is preserved quite well through a few different databases, but of course anything helps in terms of preserving history.