Hi John
I might be completely off the mark but my take on it is that whilst, as per the example of this forum covering a good cross-section of modellers, is that while that is true, many of us tend to build what we are interested in e.g. warships, sports cruisers, tugs, lifeboats, yachts, the classics (Sea Queen, Rapier etc.) etc. and with time being limited tend to concentrate on those, building either from kits or scale plans and rarely build another type of boat or ship.
There are exceptions of course, where some folks build all types of craft. I'm relatively new to the hobby and over the four years since I've started I've only ever built Faireys and I've got at least a couple more to build before that itch is scratched. I am planning to build something non-Fairey in the near future but it will be a similar type of boat i.e. a sports cruiser. Whilst I appreciate the builds of all types of models, many of which are fantastic, I've got no interest in building any of them myself, and that also applies to free plans, from well, only the one magazine now. In the four years I've been buying it there has only been one I'd consider building and that probably won't happen.
I'm guessing that in the hey day of model boating that many would have built from free plans but in recent years I don't think that is the case, as I think most concentrate just on those builds that they are interested in and find the kits, plans or draw their own.
Just my take on it and happy to be shot down!
Chris