I agree. I have wondered for years how Microsoft manages to monetize spam delivered to its disgruntled customers.
Often, I have figured it has to do with not wanting to provide "free" email services to Windows users. I don't pay for 365 or any Microsoft product other than the Windows operating system each time I purchase a new laptop. Some would say I am foolish to continue with Windows, but it dominates the pc market. Chromebooks, while I prefer gmail's ability to resist spam, are good for school kids. They just aren't compatible with the optional finance software I need on my laptop. Macs are narrowly proprietary-oriented.
Microsoft pop-ups and updates and what nots continually pressure Windows users to subscribe to services. Maybe people do just that, subscribe to 365, in order to ameliorate the annoyances. I strongly suspect that annoyances still abound even after paying for service.
Do you think they market email services to spammers knowingly? I've thought that is a possibility, too.
By the way, in the old days, you could block country codes. I did that. It was very helpful back when....