You are probably right. For EDM, cultural differences have kept the US lagging behind Europe and the UK. EDM-specific clubs are not common outside of major cities known for nightlife. A lot of EDM tours end up at venues that aren't designed for EDM. These are the conditions informing people's tastes, so probably a big factor for why bass isn't as prominent as elsewhere. There truly are fans an places where it is very much alive, just not as strong as other places IMO.

Brostep may be Dubstep Disneyland, but I'm not sure if being unconcerned with filing music in the right subcategory counts as "lagging".

The bass music underground is alive and well in many parts of the US.

Mainstream it is not, and THANK GOD for that

Pretty much every genre changes significantly over its lifetime though. It seems like you could just say you like early dubstep just like people say, "I like old school hip hop" all the time.

I get what you’re saying but the sound is so completely different it’s not a simple evolution of style.

Listen to dnb from two decades ago you can still see where current stuff comes from. Compare early Digital Mystikz stuff with Skrillex and you wouldn’t call them the same thing.