Interesting! Although I wonder if similar conditions existed with networks in the 80's - I don't know much about the period but I do know there was competition. I'd be curious to know how http succeeded in that environment, because all the factors you listed should have killed it as well.
TCP/IP faced a lot of competition (e.g. from token rings), but won out probably due to simplicity and robustness.
The current dominance of HTTP is largely due to firewalls, NAT, and possibly developer familiarity (e.g. proxying, debugging via cURL, etc.).
I wasn't online in the 80s, but I remember networking in the 90s being a mixture of HTTP, POP, SMTP, IRC, FTP, Telnet, NNTP, etc. The noughties saw an increase in protocols for P2P, instant messengers, etc. These days those seem to have consolidated (e.g. BitTorrent, XMPP, etc.), are often tunneled through HTTP, or are displaced by something newer which tends to use HTTP.
