Would I Regret Planting Thistle?

I was watching a Goldfinch fluttering around my flower gardens earlier last week and I ended up going down a rabbit hole all about their preferred foods. This led to me thinking about intentionally planting some milk thistle down at the base of a hill I have that is kind of a no-mans land, it is rocky and contains just a handful of non-descript plants.

I haven't dealt with the thistle family that much except the random bull thistle volunteer so I'm not sure what to expect. Are they a great addition in the distance or will I have to consistently work at containing them?

Thanks in advance