Most European cities where scooters (mopeds) make up a seizable portion of traffic (e.g. Paris) would come to a standstill if you "didn't do that".

The issue is more that drivers in the US aren't used to sharing the road with these vehicles.

In Paris, drivers naturally drive far left and far right on roads that have two lanes per direction to leave a corridor for the scooters in the middle.

Then 'going around traffic' is less of an issue for everyone involved.

It's legal to split lane in California.

There's a range of ways to do that. Weaving through flowing freeway traffic at 100mph? Pretty damn dangerous. Filtering up between lines of stopped cars at a stoplight? Not terribly dangerous & reduces traffic for everyone.

That's literally want you're officially meant to do according to the highway code in most of the world.

It actually reduces one's chance of getting rear-ended when waiting in stopped traffic.