Source of your claim? I'm monitoring blocklists of about 20 different VPS providers, most of them are completely clean, some are in one policy blocklist because they don't allow outgoing emails and only couple are on 2+ blacklists (of 67 monitored) because there's some noisy neighbor on the /24 subnet.
Sadly only my personal experience across multiple years. I think I was selfhosting my mail for about 5 years. Multiple Hetzner root servers using mailinabox and later mailcow. All self checks green.
