More seriously, some redundancy helps with some data corruption. We don't need capital letters; we could let the punctuation show us where the sentence ends. On the other hand, we don't need the punctuation, either; we could let the capital letters show us where the next sentence starts. But having both lets us figure out things like "did the author insert a period there as a typo, or is that really the end of the sentence?"

I get it for comments or social media statuses, but if you're writing long form text you want somebody over 30 to read, reaching over to the shift key is probably worth it. This was a good read but it was annoying, like a nice book transcribed into Comic Sans.