I guess I'm confused as to who is allegedly providing the counterargument that they should love out-groups more than in-groups?

It's rare to see anybody literally arguing it, but it's more common than not in the real world.

Oppression would be quite impossible throughout history if people weren't willing to oppress their own kind to the benefit of others.

Even those arguing for loyalty to the in-group are rarely those who would themselves make any sacrifices for that group.

	▲	estearum 43 minutes ago \| parent [-]
		> Oppression would be quite impossible throughout history if people weren't willing to oppress their own kind to the benefit of others. No what's far more common is that people change their perception (or have different perceptions) of who is "their own kind." You can actually see this happening in real time in the US with the emerging concept of "Heritage Americans." It's a way for losers and crybabies to narrow the scope of who is "their own kind" without having to openly declare that they simply don't love their countrymen.