I was not talking about making all roads the same, like the number of lines, sidewalks, curbs...etc. What I'm talking about is that between road crossings it's easier to use splines. If you have a road for example which is a bit complex (two sidewalks on each side, a separated grassy part between the roads, I don't know), and the road is almost the same for kilometres long (except a few parts), then what do you do? Place dozens of curbs and make everything out of polygons, or simply model one road, use it almost everywhere, and only do the needed parts separately ? That's what I'm talking about.
The polygon tool itself is not buggy, actually I like it a lot (a tool like that would have been awesome in OMSI). But building complex roads on slopes or hills is not that pleasant (with polygons) and about 99% of the map builders experience a lot of holes on their map. Maybe it's not the editor's fault, more like the lack of documentation, if almost everyone do it wrong.