Earlier quoted context omitted.
Yes that's very frustrating. I'm scared to even listen to new music on it because I'd try to use it for discovery but it would mistake what I listen to for what I like. Besides that it hardly recommends me any new music anyway. I now just use youtube for discovery.
They should add an incognito mode or something. You could even do this maliciously. Send someone a Spotify link to a Steely Dan song and a Skrillex song, and now yacht rock and dubstep will follow them around until they delete their account (I'm assuming the intersection between those fan-bases is vanishingly small).
Profile > Private Session