Bike frames are designed with a certain type of handlebars in mind. A gravel bike is designed and sized around drop bars, which add a lot of reach on a bike.

You get the best results by starting with your intended use and then choose the kind of bike which does it best. If you want to eat up lots of miles on the open road, a drop bar road bike just does it best. Gnarly offroad? MTB. So on and on.

If you start from the imagined ideal bike which you think is best, that is just backwards.

Most US customers don't buy bikes for commuting or touring and hence the set of ideal bikes for their purposes is fairly homogeneous.