If someone puts up a ten-paragraph post and there's something different in each paragraph I want to respond to, I can either:
a) reply once, breaking up the original post so my responses go with the bit they're responding to
b) reply once, with my responses as a single block containing lots of attempts to indicate which bit of the post each part of my reply pertains to
c) reply with ten separate posts, each quoting just a bit of the post I'm replying to.
Of these, a) seems by far the simplest and easiest.