This is somewhat ridiculous. The entire premise of Microsoft's offering is vendor lock-in.
Of course you are hostage to Microsoft. Of course they will keep integrating their services until it's impossible for you to change providers. And when they raise their prices you will pay. It doesn't make sense to fool yourself into thinking something else.
If you want separate discrete services you have to stop using O365 because it's already a bundle of services - even without email.
Unless you only want email from them, then it's not too locked in. Just not very good.
systemd has got this since early development. this, among other things (PID 1 master process...etc), was one of the reasons Poettering designed systemd. It borrowed this idea from other systems like this