Well, I guess it's all relative. When I was growing up in Massachusetts, my backyard was 130 x 250.. quite large for a "back yard". That doesn't mean I flew RC there, it only means it was large..
But, I get your point, I got it the first time around, and agree with you. I just wanted to point out that many of these "small" models can be flown in confined spaces. The Bug, for instance, was demonstrated in an area just about the size of, what one could call, a normal back yard sized area, which I would judge to be about 90 x 90 or so, considering that most frontage for home is about 90 feet wide and many home yards are rectangular in shape.
Anyway, like anything else, the wind plays a factor in just about everything we do with RC aircraft, from the smallest to the largest. It all depends on what we are comfortable flying with. For a beginner, any wind can be a problem.
That's how I crashed my first plane, a Skylark 56. I flew it in wind that was to strong for my capabilities and level of experience, and that was at our club field which is 3500 feet long!! Now, of course, well, I fly anything I want, but I am more conscious of the wind than I was when I first started out. Heck, all these light electrics can be a handful in wind.
CGr