Don't you think it'd be possible to create such a thing, which would also create labeled solder points for jumpers where traces needed to cross?
Maybe "rat's nest" already does this; I don't know what that is.
You start out the board deisgn by orienting your parts in a way that there are as few intersections as possible. Then you draw the connections, and the ratsnest lines disappear one by one. If you have intersections, you need to route around the part, or work with multiple PCB layers to get rid of them.
At that point "as few intersections as possible" becomes a bit of a lark and to maintain any semblence of sanity you have to prioritize connections, hiding all other nets.
Without that knowledge, it's impossible to create a good auto-router/layout tool. The tools often just stack components as close together as physically allowed by the necessary traces.
For very trivial stuff, it might work ok. Anything else, no chance unfortunately.