SystemD is blamed for long boot times

That is and always was nonsense. Systemd shortens boot times by starting things in parallel. That's one of its key features.

There are some things to note about that:

Systemd only starts services in parallel when it isn't told otherwise by Before and/or After settings in the service files. This makes it pretty easy to make systemd slow by misconfiguring it. You can use the systemd-analyze program to see which services held up your boot.

Systemd has a very long default timeout (90 seconds) for starting or stopping a service. It's appropriate for the big, lumbering servers that systemd was probably designed for, but it might be wise to shorten the timeout on desktops, where a service taking more than 5 seconds to start is almost certainly broken. It's a setting in /etc/systemd/system.conf.

Is the current SystemD rant derived from years ago (while they’ve improved a lot)?

I'm an early adopter of systemd. I installed it on my Debian desktops pretty much as soon as it was available in Debian, and I later started moving servers to it as well. I had long been jealous of Windows NT's service manager, and systemd is exactly what I had hoped would come to Linux one day.

Yes, the rant you're talking about is old, and yes, systemd is better now than it was then, but not in the sense of what the rant was complaining about. The rant was already patent nonsense when it was written, which has given me a very dim view of the anti-systemd crowd.

Besides systemd proper, they also spent a lot of time ranting about the journal system, which redirects syslog entries into a set of binary log files. They complained that this would make logs impossible to read in emergencies. This isn't even close to being true—any emergency bootable Linux image worth its salt has a copy of journalctl on it—and the binary nature of systemd's logs has caused me serious problems on exactly zero occasions.