rlf3, you are obviously
a riding God. Smarter than everyone else.
Of course SatNav can't see round corners any more than you can, no matter how good your observational skills may be.
If you ride around assuming that there's a fallen tree, tractor or any other hidden obstruction over every hill or round every blind bend, then you might as well stop, get off your bike, walk over the hill to check before progressing any further. You know, just to be really, really careful.
Equally, a SatNav should never be a substitute for good observation, but there are times when you can't tell which way the road is going, like no tree line, no telegraph poles, no road signs, but a little bit of live map reading from a SatNAv just makes life a little easier.
Advanced riders are taught to take corners at a speed that allows them to pull up in the distance that they can see, but even that is moderated with a bit of common sense, otherwise we would be crawling around every blind bend.
So, you don't like SatNavs. Bully for you. It doesn't make everyone else a numpty though. It's how, and when, that they are used that matters. If you can ride, alone, into a city that you have never visited, and find an address without stopping to check a map or ask for directions, then you have the navigational skills of a homing pigeon, but somehow I doubt that that is the case.