OK I see your point, whoever,
I design and build all of my own models (including the fuel tanks) , and also make up my own control lines from bulk materials.
The postings on this (and other) web site prove the a lot of "modelers" do NONE of these things.
However, I have drawn the line at machining engines, spray painting, and electronics.
To me (and I think some others) to task of rounding up the components of a working system is an impossible barrier.
Even if an "off the shelf" system took some work to fit into the plane, it would be a better starting point.