As far as I know, it is an explicitly stated goal of the systemd project to provide an integrated (compared to whatever each distribution assembled together to provide one) base system on top of the Linux kernel with the intent of making the best use of the features provided by the kernel.
It seems to me that Lennart looked at the tightly integrated base system + kernel approach of the BSDs and decided he wanted that for Linux too (in addition to whatever other influences he had), and then he made it happen.
Fwiw, apart from journald and logind that’s true for systemd as well. You can choose to run nothing other than pid 1 and these two daemons. Everything else is optional.
As far as I know, it is an explicitly stated goal of the systemd project to provide an integrated (compared to whatever each distribution assembled together to provide one) base system on top of the Linux kernel with the intent of making the best use of the features provided by the kernel.
It seems to me that Lennart looked at the tightly integrated base system + kernel approach of the BSDs and decided he wanted that for Linux too (in addition to whatever other influences he had), and then he made it happen.