IIRC, they printed more messages to the console when booting Linux with a debug parameter than Linux could handle.

Systemd developers were like "nobody can tell us how much detail to print", until the kernel developers made clear that the boot console belongs to them and if systemd doesn't back down immediately they would take away all console access. Systemd then backed down.

So you are saying two teams maintaining two systems which are working together tightly had a conflict about how those systems are supposed to work together and resolved it after some heated discussion?

Sounds like Open Source to me.

Here is an overview:

https://www.phoronix.com/scan.php?page=news_item&px=mty1mza

Here's a better[1] overview: https://lwn.net/Articles/593676/

[1] Less blog spam, less click bait, better reporting.