The thing the inexperienced systemd developers (but I repeat myself) do not understand is that "modular" isn't about some technical detail such as how you compile various features. For example, busybox intentionally compiles everything into one big binary. The features it provides, on the other hand, are still very modular in the UNIX sense. The key difference is that the tools busybox provides ("cat", "wc", "mkdir", "dd", and many others) all implement well defined APIs.
What is an Application Programming Interface (API)? It's not some function you can call, or the fact that a program understands some option ("--foo"). It is not even the documentation that may or may not be provided that describes how to use some feature. So what is it?
An API is a PROMISE .
It is a social feature, not a technical one. The functions, options, and documentation are just the technical implementation of that promise. The key part of an API is that it is a promise by the developer that if you want to interact with some feature, this is the way to do so, because while other internal stuff may change at any time, the promised API will be stable and reliable.
The problem with systemd is exactly this. Pulling a n00b move and agglutinating various features into one project is annoying and not recommended, but it is not, on its ownn, a reason to avoid systemd. The problem came when Poettering stripped down the barriers betwen features with the specific goal of removing established APIs. His stuff may compile into various separate programs, but Pottering is very careful to keep various key interfaces "unstable", specifically to not make any promise about how those interfaces will work in the future. He likes to call this hididng of interfaces "efficency" or "removing complexity". What he never mentions is that many of us used those promises, and by removing them he has at best forced others to do a lot of work to fix the breakage, or at worse made various features impossible.
A good example is logind, which was absorbed into systemd just so promises about its behaviuor in the future ("stable APIs") could be removed.
The reason many of us that have been watching Poettering's cabal for many years now suggest these changes are intentional and malicious are based on this. Occasionally removing features because of a technical need or bug or security requirement is understandable. Purposfully stripping out entire sets of features - that is, the features that allow other groups to develop with confidence that some feature they won't simply vanish - is something entirely different.
If MS acted like Poettering's cabal and removed a formerly-public API that competetors used - while promoting their own product that happens to use internal, not-publicly-promised APIs, the world would be screaming "monopoly". This happened, and resulted in several high-profile court cases.
So go ahead an prove that you don't know what you're talking about and assert that systemd is in any way "modular", when non-modularity was an explicit goal behind systemd. The rest of us are choosing to not go along with Poettering's attempt to embrace and extend Linux into a cheap, buggy, feature-free windows clone.