Question about old kana 歴史的仮名遣 and small kana

Hello everyone!

I have a question about old kana or 歴史的仮名遣(https://en.wikipedia.org/wiki/Historical_kana_orthography?wprov=sfla1).

I am a sinologist (i.e. I read Chinese) and primarily read old Japanese texts (1890s to 1945) and current academic texts related to my research. While I have been doing this for several years, to my embarrassment I have to admit that I only recently learned about old kana and the differences between old kana and the post-1945 period.

I am somewhat surprised that I did not learn about this earlier. My understanding is that this might be because the differences between old and new kana are primarily important for pronunciation and as I primarily read Kanji heavy Japanese without furigana, I might not have noticed because of this reason? Is my understanding correct?

Also, on a related note, I understand that one of the differences is that old kana has no small kana. When reading current academic texts from today, i also noticed that few small kana appear. Does this have to do with the fact that academic texts are also Kanji heavy and small kana are often used for the spelling of words that can also be written with kanji only?

Thanks for any suggestions/help!