I think this is standard. It applies to domains as well. I experienced government services blocks as well -- they send me an email, yet block my reply. I complain every time and rarely does anyone care, the support person does not escalate, so my email remains blocked, sometimes I'm told system is working as configured, completely ignoring that I am a real person and system is hostile towards me.

It's just general fragility of tech and lack of care from the creators/maintainers. These systems are steampunk, fragile contraptions that no one cares to actually make human friendly or are built on crappy foundations.