Yep I know about that, but was more specifically interested in the case of not having to make such changes and having it just work (tm). Resource-wise having a 50,000 or 500,000 default ulimit wouldn't matter. But we find out here, it matters for compatability.

But with the systemd change he mentioned (which for Ubuntu, exists in 20.04 but not 18.04) - that the HARD limit is now 512k - applications can chose to adjust the ulimit from inside the application that is not running as root. So all modern software can just, if it knows its OK, make the call during startup to increase the limit to whatever it thinks is needed. Then we dont have to override.conf systemd services every time you hit a scaling limit or think about it.