A fetish is not always, by definition, a hardcore thing. Sometimes it's about how imagery complements what the brain already imagines - fetishes wouldn't be fetishes unless they pushed someone's buttons for whatever reason.
And what makes this a "controversial" fetish (hence on the /alt/ board) is more the question of whether photography of stone age tribal peoples should be considered exploitative. I remember, on previous bara image boards that dealt with this question, that there was a decision/consensus that if it's already a public photograph and there are no obvious underage people in it, then it's fine.
This is not a tribal photograph, but comes from "Natural Man Photos" by photographer Sherwin Carlqvist. Men in natural surroundings, all without modern tattoos, shaved body hair, tanlines or even circumcisions - as primeval as can be managed.