The car argument has been raised already. I’ll just illustrate a bit further.
A path, 20m wide, asphalt, 6 lanes, one-way, car=designated, no bicycles, no pedestrians, fee, good visibility, low inclination. Oh, wait, that’s a motorway, isn’t it?
Everything can be described with secondary tags. We just need lines, they don’t even need to be paths. Maybe they are rivers? It should be clear from another few dozen secondary tags.
I’m pretty sure there’s less difference between several types of roads (primary, secondary, anyone?) than there is between different types of paths. I mean, you have for sure seen the images at
We certainly don’t need main tags for everything. But what are the criteria?
I agree that, at the moment, we are mixing the visibility with surface, with width and inclination, and trying to add some sort of difficulty scale (7 levels?! That is way too many!) in the new tag names.
Let’s then try to come up with some sensible criteria to apply. We all can instinctively tell that there’s a big difference between a stroll path next to a river and an UIAA level III scramble. But we seem unable to define it properly.