Then I'll point to the wide success of monolithic utilities such as systemd as evidence that consolidating typically helps long term.
Which is to say, not shockingly, it is typically a tradeoff debate where there is no toggle between good and bad. Just a curve that constantly jumps back and forth between good and bad based on many many variables.
systemd is also completely useless on its own. It still needs a bootloader, a kernel, and user-space programs to run.
When it comes to process managers, there is obviously disagreement about how complex they should be, but systemd is still a system to manage and collect info about processes.
Linux by itself is just a kernel and won't do anything for you without the rest of the bits that make up an operating system.