[dragonwriter]

> At least in the Western developed world, discrimination against less attractive people is probably the most potent, most prevalent and least acknowledged discrimination in the society.

It’s prevalent and potent, but it is extremely widely acknowledged. The degree to which it is seen as problematic is more variable ("discrimination", in and of itself, is simply having a factor influence a decision, and is not universally viewed as problematic.)

> There’s not even a word like racism, sexism, anti-X or X-phobia for discrimination against less attractive people.

Yes, there is, and the word is “lookism”. [0]

> It is least acknowledged because as you mentioned, there’s no one who would like to join the “ugly” identity group.

“Ugly” isn’t an identity group. Discrimination can happen on literally any basis (every basis on which a decision is made is “discrimination”), not only by identity groups.

[0] https://www.merriam-webster.com/dictionary/lookism#:~:text=o....