They're focused on the thing that'll get the most people up and running for the least extra work from them. When you say "push" do you just mean that's the default or are they trying to get you to not use another ACME client like acme.sh or one built in to servers you run anyway or indeed rolling your own?
Like, the default for cars almost everywhere is you buy one made by some car manufacturer like Ford or Toyota or somebody, but usually making your own car is legal, it's just annoyingly difficult and so you don't do that.
As a car mechanic, you could at least tune... until these days when tou can realistically tune only 10..15 years old models, because newer ones are just locked down computers on wheels.
It's actually not that bad in most states, some even have exceptions to emissions requirements for certain classes of self-built cars.
Now, getting required insurance coverage, that can be a different story. Btu even there, many states allow you to post a bond in lieu of an insurance policy meeting state minimums.
Like, the default for cars almost everywhere is you buy one made by some car manufacturer like Ford or Toyota or somebody, but usually making your own car is legal, it's just annoyingly difficult and so you don't do that.