This still doesn't answer the question: Why does RedHat allow systemd to be created, and why do they allow people like Lennart to mess things up? I don't know for sure.
I have to work on Linux (Redhat, CentOS) as part of my job. There may be some innovation in Linux, but I don't know what it would be. They invariably knock off everything that has been done before. systemd is not any different than SRC in AIX or SMF in Solaris. In the case of AIX, that has existed since at least 1995 when I started on it with (I believe) 3.2.5, and in the case of Solaris, since 2005. Dynamic i-nodes were available in JFS2 in AIX 5 which was 2001. Solaris released ZFS in 2005.
AIX has multiple page size support.
AIX has had multibos or live update support for over a decade, and then Linux came out with k-splice (another knock off).
AIX Workload Manager.
AIX Advanced Memory Expansion.
AIX Active Memory Sharing.
AIX LPARs/Workload Partitions.
Solaris LDOMs/Containers.
Those are enterprise features.
It always humors me when Linux cheers the adoption of X when it has been available for at least a decade - and sometimes two - in AIX or Solaris.
But the real question isn't "don't let Y become like Z; or why is Y like Z?", because they are both the same thing, based on X. It is, "Where do we go from here?"
UNIX was released in 1971 which is nearing the 50 year mark. BSD and Linux are all based on UNIX.
Plan 9 was developed in the late 80s to fix the problems with Unix like networking and graphics. But still used Unix as the inspiration.
Then you have Windows which was released in 1985, which is nearing 35 years.
Minix based on Unix.
Akaros, NIX, Clive, Inferno are all based on Plan 9. These four are distributed operating systems and only Inferno was released commercially and never caught on. The other 3 are research operating systems.
Android based on Linux.
iOS part of the macOS family. macOS originated with NeXTSTEP which was based on Unix.
OS/2 was a hybrid of Windows and Unix.
BeOS was not internally Unix, but after Apple went with NeXTSTEP, it never gained commercially.
There is nothing on the horizon to replace either Unix or Windows. In the next 50 years are we still going to have the same thing? Au Gratin, french fried, mashed, cheesy baked, tater tots, roasted. However or whatever you call them, they're still potatoes.
Plan 9 was thought to be better than Unix, but Unix was just good enough. Just good enough is what we strive for in an operating system?