[vostok]

Are those diacritics? I tend to think of them as separate letters just as å and ä are separate letters in Swedish. Of course, ё is usually written as е so I may well be wrong about that.

This is different from è, é, ë, and ê in French where these are all e, but with different diacritics.

[krick]

That's my impression of the statement as well. Even if technically they can be called diacritics it doesn't make much sense, not within this discussion. "Й" sounds absolutely unlike "и" and has pretty much no connection to it. "Ё" is a bit more tricky, but nevertheless — there's no another letter in Russian alphabet we could put umlaut on and get the result similar to putting umlaut on "е".

I guess "ь" has more right to be called diacritic, because it genuinely has 1 purpose: altering the other sounds. But even that is treated as a separate letter.

It's nothing like diacritics in French, German or even Latvian, let alone Arabic.

[varjag]

Й is absolutely linked with и, and it arose as alphabetic distinction from it. It appeared and disappeared for certain periods; in Russian it reestablished as a letter only in 20th century. It is still commonly collated with И in indexes and dictionaries.

> "Ё" is a bit more tricky, but nevertheless — there's no another letter in Russian alphabet we could put umlaut on and get the result similar to putting umlaut on "е".

This is a bizarre distinction: diacritics in natural languages aren't supposed to be freely recombinable.