Well if we're going to argue about which practice is a bad idea, it's
quoting by default that's now mainly to blame for these problems. All
clients can top post. Most can thread related emails. Many mobile
clients can't bottom post or can't be configured to do it by default.
The list rules about bottom posting are antiquated by predating
mobile. Quoting and bottom posting combined originate from the
pleistocene of email and can be used to carbon date its proponents.
Without quoting, the top/bottom/trim argument doesn't even come up.
I mostly agree with mattmanser.