That's just down to who you've worked for. I've worked for two companies, both well-known brands, both operating in the consumer space (nothing secret/shady), where most outbound ports were blocked.
In one case it certainly was possible to get them unblocked for access to specific hosts or endpoints but you'd have to go through an approval process that took about a week. I never had a request refused but it certainly could slow progress, although I got into the habit of trying to get all of us to anticipate what we might need and front-load such requests.
I have several (all government) clients who cannot access port 8080 from their office network. We now have a bunch of aELB rules that forward a specific path prefix to port 8080 internally. I have not yet been accused of intentionally circumventing their firewall. But I live in hope...
The fact that port 80 and 443 are less likely to be blocked is a distant, secondary factor. Frankly, I've never been on a network that blocked other outbound ports. And I've definitely never seen a network where hosted services could only ever receive traffic on port 80 or 443. Rather, I think it's more (if not entirely) a matter of people justifying the use of web stacks to implement services which cry out for simpler solutions.