alt Hacker News> None of those are digraphs or have diacritics, each is a single letter/character
Okay, you got me, these don't have diacritics, but other Slavic languages do. Unicode committee decided that some of these are separate letters (Ѓ, Й, Ё etc.) and some are not (Ў), but still doesn't make these "trivially provable to suit Slavic languages better".
> Nj (this "letter" is made up of two other letters)
Indeed it is. Invented in 1818. E.g. Russian uses two "нь" for the same thing.
My point is, even if I may confuse my linguistic terminology from time to time, is... How does all this make Cyrillic "trivially provable" to be better suited for Slavic languages than Latin script? It's all the same: invent new letters or new letter combinations, or slap a few diacritics on top. And when that is not enough, borrow from Latin. E.g., j in Serbian, ї in Ukrainian and й in Russian for the same sound.
Some of this was a top-down overhaul of the writing system in the 19th century. Before that it was an awful mess and people just "vibe-wrote" the weird Slavic sounds using latin how they saw fit; try reading some old writings from that era. Or read some modern Polish or Czech text :-D