Plus, for any given large organizational customer HTTP/HTTPS are allowed through their firewall/other network security apparatus, wheras other ports require a b

Plus, for any given large organizational customer HTTP/HTTPS are allowed through their firewall/other network security apparatus, wheras other ports require a bunch of special exceptions from the security people to use. Said people often refuse to give exceptions no matter how reasonable the request might be, so everybody ends up doing everything on port 80 or 443.