Fair, I don’t see anywhere that they are explicitly marxist or leftist (though I feel like that should be obvious by the name). They do however, linked immediately above the screenshot you posted, state that they are not a liberal instance and don’t want to be. They also state that they would like to see another instance take on the role of a mainstream, liberal instance. I think it is extremely unfair to expect lemmy.ml to cater to liberals when they explicitly state that their instance is not a liberal instance.

edit: link to the post: https://lemmy.ml/post/70280 (it can be found linked on their sidebar immediately above their rules)