Because systemd makes certain desktop related tasks easier to present to the user. It's a huge loss imnsho because linux on the desktop wasn't held back by a lack of such niceties but by market conditions, at the same time linux on the server will be held back by systemd because of its tendency to do things 'its' way.
I haven't seen any single subsystem harm the linux eco-system as much as systemd has and while I understand the desktop vendors clout in this the server is where linux shines and that was territory that was hard won.
If all systemd had done was offer an alternative init system then that would have been a non-event, to take over the entirety of the linux system side tried-and-true and battle tested utilities is irresponsible at best and dangerous at worst. It wasn't broken, so it did not need fixing / rewriting.
I haven't seen any single subsystem harm the linux eco-system as much as systemd has and while I understand the desktop vendors clout in this the server is where linux shines and that was territory that was hard won.
If all systemd had done was offer an alternative init system then that would have been a non-event, to take over the entirety of the linux system side tried-and-true and battle tested utilities is irresponsible at best and dangerous at worst. It wasn't broken, so it did not need fixing / rewriting.