OpenLaunchD was a port of Apple's LaunchD (which is about 17 years old) to FreeBSD, and perhaps other OSes. LaunchD itself came out in the mid-2000s, as part of some MacOS upgrade. I actually remember it showing up; at the time I was administering dozens of Macs in an elementary school. It followed a wave of efforts in academia and research to make systems boot faster by re-engineering the init system. For example, my office mate around 2005 or 2007 (I was in a systems research group) was working on a parallelizing init system as a prototype. LaunchD seems to work very well, within Apple's MacOS ecosystem. The beautiful thing about that ecosystem is: All parts are under Apple's control!
I remember hearing about OpenLaunchD a few years later, as a port of the Apple open-source code of LaunchD to FreeBSD. May have been around 2010 or 2012, when I was busy with my day job. I vaguely remember it being a minor side project of a small number of people, and it ending when they lost interest.
In the meantime, the Linux ecosystem tried to solve the same problem. First came a pretty simple parallelized init system that some distribution (I don't think it was RedHat) used. And then came SystemD and Lennart ... and that's when things went to hell in a handbasket, as far as civilized discourse is concerned. Many people (me included) are of the opinion that SystemD is a very good system, which functions well, once you learn how to use it and put yourself into the correct mindset for understanding how it works and how to use/configure it. Many other people (again, me included!) claim that SystemD is a terribly badly written piece of software, inflexible and hard to maintain, and impossible to work with as a developer because of the sheer obnoxiousness of its chief architect/developer (aforementioned Lennart). Note that these two statements do not contradict each other, as they talk about different aspects of the thing. I know there are people of differing opinions, and I respect those.
Discussions of SystemD nearly always turn into a mud-flinging game, and end badly. I suspect that what really has happened is that SystemD has sucked all the oxygen out of discussions of improving the init system. Note that Lennart is de-facto employed by RedHat, the 400 pound gorilla of Linux distributions, which together with IBM (its corporate parent) and Intel has the decision-making authorities for Linux in its pocket.
Today, Linux is about 95-99% of the Unix market, and much of Linux are now extremist religious followers of SystemD, with a small but very vocal minority of just as religiously fervent SystemD haters and their favorite Linux distributions. The second largest part of the Unix market is MacOS, where all control of technical decisions is done in a round building in Cupertino, and they are firmly using LaunchD, which seems to be serving them very well. The remainder of the Unix market (AIX, HP-UX, SunOS/Solaris, *BSD, ...) is tiny and from a financial viewpoint irrelevant. Sun/Oracle has its own init system (it's called SMF or something like that), which is quite similar to LaunchD. I think AIX and HP-UX were using traditional SysV init last I looked, but they are simply not important any more. The various BSDs don't have the manpower to engineer a new init system. And it seems there are not even volunteers available to port the (open-sourced-) Apple LaunchD.
But why does this matter? For an experienced BSD user or admin, managing a system with the rc scripts works really well. With modern SSDs, boot time is very fast, and the speed of bringing up daemons is no longer the limiting factor (hardware initialization and the BIOS is the limiting factor today). Amdahl's law tells us that further optimization here is pointless.
