The vast majority people didn't yet use email back when bottom posting was good etiquette and top posting was discouraged. They're simply not aware of the concepts, or the controversy, at all. Even old-fashioned snail mail letters, for those who still remember such things, didn't usually include quoted passages, even though getting a reply to one's letter could easily take weeks if not months.
I remember around the time top-posting had taken over, someone on a mailing list being upset about having their mail cut up and quoted inline by someone else. Can imagine today many might react like that if they ever encounter nicely formatted mail replies.
I felt people were unwilling to take the responsibility for communicating properly, and so they took the easy route where they could shrug their shoulders and say "I included all the context."
I only ever got complaints from people who were confused by the quoting style or didn't know what the email was about. I'm not sure if it's still true, but at the time, Outlook didn't use threaded view mode by default and most people didn't know about it. FWIW I work in manufacturing and not in tech, I expect the level of competence in tech is a little higher, though I also hear how people moan about having to learn the tools they use every day, so maybe there's little difference.
I even started to avoid inline responses and comments, many find even that confusing.
then enforce it by policy across the org, and watch the chaos as people read before speaking.