Legit question: is there any other service/company on earth that bans you for having multiple accounts? This seems like an insanely restrictive policy. One of the defining characteristics of internet communication is that you can have a “work persona” and a “home persona” and maybe another one for your hobbies, another one for your porn browsing and gambling, another one for your aunts and uncles. To deny this basic, universal concept is backwards and frankly shouldn’t be acceptable to anyone.
Internet companies have decided to deny this right the moment they figured out that your identity is valuable. Nowadays Google and FB, among others, will punish you if you use different online identities without their knowledge.
And while I love complaining about policies and behavior of FB, Google, Amazon etc, this one makes sense.
Almost always you ban person, not account - so standard is to allow one account or to require accounts to be clearly linked (for example, a separate bot account that is clearly declared).
GitHub disallows multiple free accounts in the TOS, meaning identity separation seemingly implies a continuous subscription cost forever. I'm not aware of any high-profile enforcement, but it's there.
It would be so ridiculous for Microsoft to have a one identity policy because Microsoft software accounts are generally provided by employers and tied to them, I have 4 MS identities (personal, two companies and university) and MS does not provide an option to use a single identity for that.