Email is another clusterfuck of a protocol (well, several protocols) that barely functions despite dozens of modern pseudo-standards plastered over it. I’ve written extensively about that too.
DNS is frequently the source of amplification DDoS attacks. It’s another protocol that made sense once upon a time but has struggled to keep pace with modern advancements in technology
IRC is probably the best of the bunch here but even that has struggled to keep pace and can be subject to undocumented behaviours (like line length).
…and these are the protocols still in use. The ones replaced by HTTP were either crazier or over simplistic that they offered nothing over HTTP.
I’ve written my own clients for every one of those examples and had to deal with the pains of their protocols. I’ve also written my own web browser. And while HTTP has some warts too, I’d take that over FTP and SMTP any day of the week.