Which writing style standard does that correspond to?
This is an internet discussion board with people from diverse backgrounds. Informal quotation style is common. Your comment is the first time I’ve seen someone assert that new paragraphs should start with a quote.
Not sure which particular standard it is but it is a thing. Agreed that it’s nitpicking though, it’s pretty easy to understand the boundaries of the quotation either way.
It's common practice when dealing with sites and clients that don't have fancy quoting features, going all the way back to USENET forums and probably before. It avoids just this ambiguity when you might be mixing quote and commentary.