[ggm]

I could believe this is a filter designed to simplify conformance to some YT standard.

I could believe this is a side effect of something else.

I could believe its a problem with some output devices (sw) of the nature of "oh I'm ASCII I can't handle UTF-8 encoded data" which doesn't have a good default.

Is there some more direct profit/IPR motivated approach which directs this format of all others should be removed?

[altairprime]

It differentiates human-created content from AI-created content in a space where AI can’t perform competitively at all. So, just as with Crunchyroll, better to kill the complex human artistic subtitles so that people don’t get used to their boring “could be machine, could be human, who cares” slop (and, as a bonus, so that human moderators aren’t required to evaluate whether the subtitles are offensively shaped).

[CamperBob2]

It differentiates human-created content from AI-created content in a space where AI can’t perform competitively at all.

Well, that certainly remains to be seen.

[altairprime]

Indeed. Fortunately, “cannot” is present tense, not future tense.