While you may not need support for the game. The games would not do as well as they do without it. They are predominantly an online multiplayer game. I am no the biggest Tekken fan, but I am a pretty big fan of Street Fighter, I have over 1000 hours on SF6. If it didnt have the good online multiplayer, and just had just had the offline and single player stuff, I would have something like 100 hours maybe and would have moved on to other games.

And that makes a big difference, to how much I am willing to buy into both characters and costumes, and also the next game.

Tekken 8 and SF6 still have good(for fighting games) single player stuff, but you are looking at a simple story and some arcade modes. SF6 has a bit more of a single player RPG almost for its single player, and I have managed to sink around 80 hours into that, they add more with each new character and I believe it is free.

And to go back to Tekken, Tekken 3 had 22 characters, While Tekken 7 had 36, which then increases to 51 if you add in the addition characters, Tekken 8 currently has ~40 with more being added. They are fine games, with all the content that you want(mostly) in the base game, but the biggest difference between Tekken 3 and Tekken 7 or 8 is it isnt being replaced in a couple years by a new full priced game, it is getting patches and support, additional mechanics and moves, new characters. And the online/competitive community can thrive.