I don't want to disagree too hard with this, because I, too, have been uncomfortable with the march toward making it very difficult to build a Linux system without things like systemd (I actually don't have all that much of a problem with systemd anymore, but I also value choice).
But no one company can deprecate anything. The source is all there, under permissive licenses. If people want sysvinit or openrc (etc.) to work well in order to build systems without systemd (for example), they are free to maintain, support, and evangelize them. And this happens, to some degree. If it's not happening to the degree we're all happy with, then we should pitch in to help, either with our labor, or financially. Otherwise we don't really get a say.
Doesn't matter if some hobbyists still run Gentoo with openrc and X-Window with Windowmaker and all the classic interchangeable daemons and components that Systemd replaced (and with which it is incompatible)—it matters that any commercial competitor's only realist option, short of a massive and risky investment, is offering the same things Red Hat does, but with less influence on those projects. They want it to be expensive to build a competitor that's not a Red Hat knockoff—and if that's not what they wanted, well, somehow they took a whole bunch of steps over a span of years to make it happen anyway, by accident I suppose, but the outcome's the same.
Don't forget alpine is also openrc and it is far more used by corporate tech than gentoo. Especially as a base for containers.
Somewhat jaded opinion after many years in the business, but these companies exploiting OSS for profit have learnt from how Microsoft's moves have played out over the years (and are now making their own mistakes). Given the only way they make money is by providing support, obviously they're going to go the MS route (make operation arcane and complex, as per your first point).