The average internet user probably has no idea what DNS or HTTPS are, let alone DoH (which even I as a technical user had forgotten existed before I read this post). Defaults matter a whole lot. I haven't formed a definitive opinion on DoH but either way saying "you can configure it so it doesn't matter" is not reasonable in my opinion.
It's interesting that when Russia started blocking access to some popular websites a few years ago, the instructions for installation of VPN were found in all places. The case - then, for example, attempts to block Telegram servers lead to unexpected unblocking some forbidden sites, like kasparov.ru - shows how some networking skills can be grown en masse in a short period of time.
So, yes, average Internet user isn't very familiar with DNS. Maybe privacy wars will lead to growing awareness in this area though.
