As a user you probably don't know, and maybe don't care.
This is more for developers, technology is not magic, vendor/technology-locking can be problematic. It's not like systemd was made by bad people with bad intention. You may have heard of X11 too. The list could go on, there is a big amount of legacy in our technology, some would just keep it that way. But some argue for changes thus discussing (and criticizing) those legacy, why it fails on some points and what to do/build from that.
So right now if you're a desktop user, I don't see why you would bother indeed. This discussion are still interesting to some devs, for instance here I learned about dinit, and it's code is damn small and clean, hence it was informative and I will definitely try it.