1. It's only for information so people can choose when appropriate
2. I personally care less about how people posted, except occasionally it's
really tired for scrolling down 200 lines for one comment, and that happened
once a while. Other than that, I read their contents and care less how did
they post.
3. I hope those who couldn't appreciate other posting styles and made such
comment as "top-posting is without mercy" could at least understand why some
people choose this (or other) style.
Other than the above - I am just like what you said - " People can post in
whatever way they want." - but those are not nonsense