How so when no published material uses a double space? Did anyone notice and change their approach because of it? Why should HTML rendering change that?
People double space because that is what they were taught. People single space because that is what they were taught. Few people make the effort to change their ways for something they perceive as trivial and which they don't even notice while reading every single day anyway.
I think that, outside of journalism, very few people were "taught" single spacing. I suspect that mostly, non-journalists who use single spacing between sentences are people who learned by reading tweets, SMS messages, and Facebook pages.
People double space because that is what they were taught. People single space because that is what they were taught. Few people make the effort to change their ways for something they perceive as trivial and which they don't even notice while reading every single day anyway.