I feel like there are 3 kinds of people who play TF2 (and aren't on trade servers/mariokart/etc)
1. The OG 6s player: They want the game to be based around a player's skill. If achieve something, it was because of your raw ability to click on things. Your team and you have practiced with what you consider the, in-general, best loadouts.
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Go play Osu nerds
2. The OG HL player: They want the game to have a malleable meta. New strats can be found in a day by studying how all elements of the game interact. They want teams to be able to develop around all of their individual strengths, and enhance individual strengths through weapon choice. Different playstyles of classes result in a teams that can play drastically different from eachother.
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Go play Dota nerds
3. The OG pub player: They play TF2 for the casual game that it is. They don't understand (or don't want to) why the choices they make in pubs aren't effective in other formats. The experience of killing other players is enough for them. Any way that helps them kill players easier is welcome.
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Go play CoD nerds
These seem to be the major PoVs that people argue from when discussing TF2. I think it's just fine that these stay separate areas of the community, with some overlap between each. Infact, I think 4s could provide for some nice overlap between the 6s and 9s players, offering more diverse classes and weapons, but still having the same focus on very skillful individual gameplay.
I do disagree with Pyyyour about changing 6s that much though. 6s has been well established as what it is, and changing it would largely just hurt the current playerbase. Imagine if you suddenly updated Quake Live with all kinds of silly new special abilities. It's just not the experience people are looking for, it's not what the people who play are there for; it's something else.
Also another question to pose here: What is TFTV's view of 4s? I've only caught some comments about it that generally bash it (me included to some extent), but I feel like it's a really nice compromise for people who want to see a lot more out of 6s, but still want the general feel of it.