Combining ways is more than just taking a clump of ways and merging them together. You have to merge the end of one onto another. So it still creates a single flowing line. On that last image I think you could merge ways and make that entire thing out of 5 ways, assuming everything about them is the same which I dought (name=?).
Basically it’s telling you, ‘you can’t stick these ways together end to end, cause that’s just a tangled cobweb of ways, not a set of ways in a line’