Oh my gods, YouTube comments render correct sentence structure, with two spaces after punctuation.
I'm so fucking happy.
Except.. fuck you Google, for various other justified reasons.
This is a sentence. This is a second sentence.
By carefully highlighting over it, you can tell the above text was rendered improperly.
The proper way would be to have two spaces..
This is a sentence.·This is a second sentence.
This is a sentence.··This is a second sentence.
I've researched ways to have a traditional website have properly rendered text, maintaining two spaces after punctuation. It is possible, but it is not nice and may not work well under enough circumstances that it's too risky to implement.