> the QWERTY keyboard layout exists to prevent typewriter keys from jamming

even if it is true (is it a myth by any chance?), it does not mean that alternatives are better at say typing speed

As someone that makes my own keyboard firmware, 100% agree. For most people, typing speed isn't a bottleneck. There is a whole community of people that type faster than 250wpm on custom, chording-enabled keyboards. The tradeoff is that it takes years to relearn how to type. Its the same as being a stenographer at that point. Its not worth it for most people.

Even if there was a new layout that did suddenly allow everyone to type twice as fast, what would we get with that? Maybe twice as many social media posts, but nothing actually useful.

One don't need to be a scientist to take a look at own hands and fingers, to see that they are not crooked to the left. Ortholinear keyboard would be objectively better, even with the same keymap like QWERTY, but we don't produce those for masses for a variety of reasons. Same with many other ideas.

If I recall correctly, QWERTY was designed to minimize jamming. The myth is that it was designed to slow people down.

Whether it does slow people down, as a side effect, is not as well established since, as another person pointed out, typing speed isn't the bottleneck for most people. Learning the layout and figuring out what to write is. On top of that, most of the claims for faster layouts come from marketing materials. It doesn't mean they are wrong, but there is a vested interest.

If there was a demonstrably much faster input method for most users, I suspect it would have been adopted long ago.

It's been debunked by both research (no such mention at the time) and practice on extant machines.