Shouldn't playing accelerated games where everything moves faster than it normally should be considered cheating in speedrunning? I don't understand how certain players are still getting away with this.

Depends... If it is a setting like battle-speed that you can set to e.g. 2x / 200% in the game's menu or another game acceleration that the game intends to balance out differences in PC hardware (some old DOS games have this) then those are mostly allowed. And usually mentioned in the game/category rules that these are preferred settings/usage.

On the other side if you're running a game in an emulator and speeding it up in a way that is only possible through the emulator like some have turbo options, then those are usually considered cheating. I don't know of any game allowing such a thing.

Naturally I have a reason for asking.

https://www.speedrun.com/sfalpha/forums/3368o

it's not possible for SFA to natively run as fast as some of the top speedrunners are doing here. Even if you play the arcade in turbo mode the in-game timer and gameplay doesn't move that quickly no matter what you do. The only way this is possible is if they're using an emulator or tools which speed the game up to give themselves an unfair advantage. Speedrunners could feasibly smash the WRs in Super Mario Bros. or any other game by making it run faster but technically this would be considered cheating and for good reason.

I would message the moderators about this on- and off-site. Some of the game's moderators were online recently. Or you could ask in its Discord.

And you've responded to an already existing thread, rather than creating a new one so they might have not been notified.

+1 on the make moderators aware.

I haven't looked into any runs, but from a glance at the leaderboard there's only emulator sub 7min runs. It could very well be that mods are aware of emulator being straight up faster. There might not be any cheating involved. I know that old real hardware can very easily be slower than emulator from my own experience. But sometimes it does not make sense to split the board in a small community. Just my thoughts about that. Anyways, that's my thoughts and I'm guessing, not knowing the reason.

Thanks for the feedback. I left Tenka a message just now.

As for emus accelerating the game, I also posted a video of someone playing the arcade SFA in turbo mode on M.A.M.E. as a reference point to compare the in-game timers to as well as the general speed of the game. From the round start the in-game timer should only count down to 88 in ten seconds, if not less depending on whether performing a Super Art temporarily freezes the timer, not speed it up as in the speedrunner videos in which the timers read 86 and 85. Both the Capcom Arcade Stadium 2 and Street Fighter 30th Anniversary Edition versions of SFA run the same as the arcade.

A1Major is ranked #1 in the Arcade Normal speedrun. He posted highly dubious videos on YouTube claiming to all perfect both SFA1&2 on Expert difficulty, yet never proved it in any case. As someone with extensive experience with the SFA series, let's just say I don't believe he actually did what he claimed and we'll leave it at that.