That's a good point, and an interesting question. If you change, but the algorithms don't acknowledge that change and treat you the same, how much is you identity in your own hands, how fungible is it?
We could add lots of "I no longer think that" forms, but I suppose a lot of it isn't because you're sorted into the artist-folder, but recommendations because of your past actions that aren't easily changed.
> Is there a plot dividing the individuals into manageable groups?
I don't think so, but I'm not sure it matters. The end result is similar, only that there's not one large conspiracy that's trying to herd you into thinking a certain way. Instead, it's a multitude of interests that are pulling you into their direction and you kind of get pulled to where most of them are in your niche of the world. But in either way, you do get pulled. Can you opt out? I'm not sure, but you can probably limit your exposure by e.g. not watching television, not reading news sites, not spending time on Twitter.