In practice, I see people boot Linux desktops under three conditions:
1. Once in a great long while, perhaps when there was a power outage or a critical system update.
2. Daily, for a few people who shut down their computers when they finish work for the day and boot them in the morning. (I never understood this.)
3. When something has gone quite badly wrong.
Outside of that, there are desktops which hibernate, laptops which hibernate, and phones which are running Firefox OS or Android and boot about once a week.
If you have a journaling filesystem and no weird hardware, desktop boot times are not a problem.
not a huge fan of systemd either, but I'm sure that if computers were able to boot in milliseconds then some of those practices would change.
Also, it's not only about desktop. Autoscaling of virtual on demand servers can greatly benefit of extremely short boot times. Surely you could use a simple and highly optimized boot system in such cases, but why not use the same if it works well.
It seems to me that it's more about systemd developers' attitude than with the actual goals. Perhaps the same goals could be achieved with a more modular approach.
The important thing is that distributions (or components that manage the deployment of services, e.g. package managers or custom service management solutions) need a simple yet powerful way to express their requirements. Not sure this requires this level of integration which appears more like a way to force people to use it (or simply because it's simpler to approach this problem by throwing away the complex legacy).
Given that Unix has been booting successfully, safely, and rapidly for several decades, I would venture to agree that 'the same goals could be achieved with a more modular approach.'
Which raises the question: why systemd? And the answer: desktop linux people, who are already mired in a world of overcomplicated and incomprehensible quarter-engineered freshman-level bullshit like gnome and dbus and pulseaudio and on and on, are sure that their problems are everyone's problems. In some cases it's because they don't know any better, I'm sure. But nevertheless, infecting the rest of Linux with the desktop philosophy is an extinction-class mistake.
1. Once in a great long while, perhaps when there was a power outage or a critical system update.
2. Daily, for a few people who shut down their computers when they finish work for the day and boot them in the morning. (I never understood this.)
3. When something has gone quite badly wrong.
Outside of that, there are desktops which hibernate, laptops which hibernate, and phones which are running Firefox OS or Android and boot about once a week.
If you have a journaling filesystem and no weird hardware, desktop boot times are not a problem.