That way doesn't necessarily work too well particularly when there's a focal length you're considering at the end of one of the ranges - zooms aren't just used for their perspective changes, particularly lower end zooms get a lot of sheer convenience use - that is, the 50mm end of an 18-55 is often used simply because it's what the person has on, and it takes less effort to turn to 55 to zoom rather than to walk up and shoot at 30. Likewise for 18mm, I doubt many people actually have too much use for an 18mm prime on a crop but if you apply the logic of looking at focal length history, a lot of the time 18 will get used simply because it's the easiest way on the 18-55 to get everything in without having to walk back a couple of steps
Except if you would have to go back a couple of miles to get everything to fit in, or if you were to step back other obstructions would enter the view, or if you were to step back you would have to knock down a wall. There are plenty of reasons why someone would want an 18mm or wider lens, 18mm is only 27/29mm on a crop, not even close to a stand 24mm prime on FF.
i agree that people might not always use a zoom lens appropriately but many people will find the extreme ends of a zoom lens to be the most interesting places to be, the middle ground tends to produce fairly boring photos in many situations. The fallacy of looking at focal length usage with zoom lenses is you might think you want an 18mm prime and a 50mm prime, but really you want a 10-24mm lens and a 105mm or 70-200mm lens.
You will also find the same sampling issue when people only use prime lenses, since it takes more time and energy to swap lenses people will tend to stick with 1 prime lens on their camera rather than continuously swapping lenses at every photographic opportunity. Furthermore, people would be more likely to use certain prime lenses for alternative reasons than pure focal length, e.g. after paying a load of money for a 35mm f/1.4 L they might use that far more often than a 50mm lens, except from their photography a 50mm lens may make far more sense (I often see people cropping photos from a 35mm lens to have the same FoV as a 50mm lens, their only reason for using the 35mm lens was because it was so expensive relative to their nifty-fifty, still the wrong lens to use). You wont get this bias using a suitable zoom lens
To really decide what focal length you want you should set the zoom to a certain prime length and do a whole days shooting to see if you like it, compare that with other focal lengths.
Contrasty to popular eleif, it is perfectly possible to use a zoom lens like a prime, simply tape down the zoom ring and go have fun.
