Firstly, dynamic IPs are quickly reused, so if one customer get an IP onto a bunch of firewall blocklists because they were operating services that got exploited (like an open relay for spam, email backscatter generator, dns that was used for amplification, smb that hosted on-click executable windows malware...), this means some random unrelatimg customer will now have problems with their internet connection. After a while, you could poison a large chunk of the pool, then they have to not just deal with you, but also a bunch of other angry customers as well as beg all the firewall vendors to unblock those IPs.

If you get static, you keep that IP for a while. You suffer the consequences of your bad setup, you have to deal with FW vendors and after you leave, the IP will be offline for long enough that it will probably "cool off".

And secondly, while I don't like it, we need to keep in mind net neutrality was not written for selfhosters. It was written so an ISP can't zero-rate their own streaming service, or block their competitors. It was about internet access, not internet participation. The ownerwhelmimg majority of people are not and don't care to be "on" the internet, they want to "access" things that are on the internet. That's why NAT is still everywhere.