If users want to forgo that mechanism why shouldn't they be allowed? If I'm in a typing competition and am typing a word with a repeated letter such as the two l's in "all", you would never expect me to have to press the l key and wait for the computer to automatically type a second l until I released. You'd expect me to just press the l key twice because it's faster and that wouldn't be considered a "hack". Why would you expect anything different for Tetris players?
As for Mario, it's just a slightly more realistic game in terms of you controlling a set of pixels that represent a person instead of blocks. Mario doesn't move from one column to the next, he smoothly travels through all the pixels between columns because people in the real world move smoothly. Tetris blocks aren't real world objects though so they can move one column at a time. If it only takes one frame for a block to move one column, why shouldn't I be able to move the block one column every frame?
Also, in the official game, if you use DAS you move at 10Hz (moving once every 6 frames). It looks like top players can tap at around 20Hz. That's only 2x faster.
Sure you could make a no hypertapping or rolling category for Tetris. Calling better techniques a glitch seems wrong, though speed runners often disagree on what exactly constitutes a "glitch" anyway.
We're not created equal, welcome to literally every sport EVER.
I wouldn't have banned it, but I would understand if they decided to have separate categories for hypertapping and "regular" play. Rolling seems to have fixed the problem.
Generally speaking regulated sports tend to draw lines here too, though obviously some draw them fairly far into the injury territory. Most of those are explicitly fighting sports though.
OTOH, almost every sport hurts at pro level, and I think it's safe to say that all pro sports are unhealthy, except a few of them. E.g. Federer has serious issues with his knees, has had more injuries than an average 60 year old man.
The most obvious is really that while the case for rules against performance enhancing drugs is usually that they just give an unfair advantage, if you look at what's actually banned and what's not, and how natural advantages are treated, it seems pretty clear that most banned substances are also the most harmful, while others skate under regulation. Esports hasn't even reckoned with this yet afaik, even at pro levels. We'll see where we're at in 10-20 years as it mainstreams.
As you point out in the other branch, that's kind of motivated largely by PR concerns. People are mostly ok with basically anyone ruining their body slowly for a job (unless it's their own), but they balk at rapid injury. My point is really just that hypertapping potentially gets very close to this line, and that's a big part of why there was a drive to find a replacement technique or even ban it from competitive use.
Anyways, there's a lot more research into how to do high APMs with a keyboard and mouse ergonomically than there is with an NES controller, which also has a hard and shallow throw compared to either of those and a very unergonomic shape to begin with. There's a lot of reasons they aren't obviously comparable to each other when talking about the RSIs they can cause.
For example, in Super Mario Brothers non-TAS runs, the rules are based around the controller and execution environment. You are not allowed to modify the controller or tilt the cartridge, but that's it.
Having the rules only limit the tools required, just like in sports, is quite elegant. If somebody figured a way to play faster with their teeth, it would be allowed, and rolling the controller is just something like that.
On the other hand, people found out that you can perform certain feats in SMB by pressing the left and right button at the same time. This is considered impossible with the standard D-Pad (without e.g. cutting it in the middle), so that is banned. At least until somebody figures out a way how to do it with the standard D-Pad.
And while it's not true for most 2d platformers of smb's era, performing repetative button actions to move faster than the standard acceleration curve allows became very possible in 16bit games and a later, and you'll see those used in speedruns all the time. Usually a repeated dash, but sometimes weird stuff like running backwards, jumping in certain ways (smb actually has one of these), or rhythmically pumping the shoulder buttons.