Most services, including email providers, spam databases, and "ip-ban sites" have clear documentation, in terms of how to get on their good side, if needed, and it is often surprisingly straightforward to do so. Often it's as simple as filling out a relatively form.
Have you ever tried to use it? Because I fought for about 2 months with both Google and Microsoft, trying to self-host my mail server, to no success. The only answer was amongst the lines 'your server has not enough reputation'. Even though perfectly configured, DKIM, DMARC, etc. Now imagine a business not being able to send a message to anyone hosted on Gmail or Outlook, probably 80-90 percents of the companies out there.
I feel you. I had my email on OVH for a while, but they handle abuse so bad that Apple just blanketed banned the /17 my IP was in. And I was lucky that Apple actually answered my emails and explained why I was banned. I doubt Microsoft and Google would give you any useful information.
They claim that, but everyone small I know who self hosted email has discovered that forms don't do anything. I switched to fastmail 15 years ago and my email got a lot better because they are big enough that nobody dares ignore them. (maybe the forms work better today than 15 years ago, but enough people keep complaining about this issue that I doubt it)
