It's slower for sure, but capitalization does impart information: beginning of sentences, proper nouns, acronyms, and such. Sure, you could re-read the sentence until you figured all that out, but you are creating unnecessary hitches in the reading process. Capitalization is an optimization for the reader, and lack of capitalization is optimization for the writer.

Its just a convention. You just get used to it. Whether we like it or not, written language is heading that way. Readers don't generally read letters in words anyway, they read the whole word after a certain literacy level has been achieved.

I think capitalization will slowly go by the wayside in most media, but one hill I'll always die on is punctuation. "i'll go" vs. "ill go"... the latter is just too crude. Many gen Z/alpha do omit it, though.