I'd say it is true. We have about 2 dozen friends we camp with. Of that number, us and maybe one or two others use the oven once or more/trip. the others vary from never in many years to maybe once or twice/year.
We dry camp a lot, but even then, we do almost all our cooking with the "Maytag" firepit or dutch oven. In a week of camping, we will use the oven maybe once for muffins for the week, and if we do a potluck dinner, maybe for that.
That said, we do like having it.
And unless it is the bigger (taller) oven, not the shorter one std on many trailers, it really is not all that usefull anyway. hard to get things to cook as you would want. the taller one is better, which is what we have.