Systemd is not obscure or a blob
I am sure that in many ways, systemd is neither obscure or blobby. However, it seems to me that it is a lot *more* obscure and blobby than any collection of more or less sensibly named shell scripts.
I wanted to get a debian install to do automatically a networking thing on boot up some time last year. After a few hours of reading systemd doco and tutorials &etc I just gave up without progress ... it really wasn't worth the candle. In contrast it would have taken me almost no time to get something functional working with a few lines in rc.appropriatenamehere.
I can believe that systemd might be excellent if you really cared about the design and implementation of handling startup stuff in an efficient and elegant manner. But I have different things I care about, but still want to get a few things working to my taste on startup, ... and systemd offers me not only no worthwhile advantages, but obscurity (or perhaps just poor documentation), and obstacles.