It's also because knowing where the escape hatch and how to use it requires greater than average development skill and finesse and it isn't at all obvious when this is required.
The people who use these platforms aren't usually able to tell what kind of problem requires a developer and what kind of problem requires them doing just a bit more research. They're usually vaguely aware that the limit is out there somewhere but in the specific instances when they hit it they often don't know it's happened.
I've also seen some low code platforms get a little excitable about the idea of nearly or even fully reinventing the turing complete programming language to introduce more flexibility to their platform and make that their escape hatch. This is when things go really downhill.