Yeah, thinking the same with regard to the Ramones. They are name-dropped so often by bands that came since—pretty sure it is not because of a t-shirt.
It's even more prolific than that. Ramones-core is a sub-genre of pop-punk, and it's awesome. Teenage Bottlerocket, Screeching Weasel and Swingin' Utters are some examples that come to mind.
They're definitely a household name because of the tshirt, same with Joy Division