Which doesn’t help traffic one iota.

So, no, one is not obligated to yield, but at some point you’ll do it anyway if you value your passenger side door panels.

In Seattle, often times you can't move out of the lane, traffic's too thick. Which is why the person in the right lane needs to make accomodations to those merging, and the person merging needs to do their part by accelerating to speed of traffic. It's a cooperation, and when the mergers don't do their part it fucks it up for everyone else. I have to disrupt traffic flow because your Mustang can't accelerate to 60mph in a reasonable amount of time. Or I don't let you in, now everyone behind you on the exit ramp gets to slam on their brakes. Given the choice, I'll screw up the exit ramp by not yielding to a slow-poke rather than screw up multiple lanes on I-405 by slamming on my brakes or making a questionable lane change.

On the flip side, if I've accelerated to the speed of traffic flow and you don't want to let me in, I'll remind you that in the Chicago-style school of driving where I got my black belt, the turn signal is a warning and not a request.

EDIT: refuse to adjust their speed to accommodate drivers merging onto a 3+ lane highway/freeway

Wait a minute, what? The general traffic lanes have absolutely no obligation to adjust their speed to accommodate anything coming down the entrance ramp except an emergency vehicle. It is the responsibility of those merging from the entrance ramp to adjust their speed to the flow of traffic. It's in the driver's manual of three states I've lived in, and I'd be surprised if it weren't universal.

Consider if you were driving a 80klb GVWR semi. If the law required you to yield that could make for an incredibly dangerous situation.

If I am out accelerating you in a goddamn ford fiesta which does 0-60 in 11 seconds... well you're probably not driving correctly.

FYI, mid-michigan also sucks for this sort of thing.

All it takes is one stupid/wrong move and you have a massive pileup.

Most of the speeding accidents I've seen along I-5 tend to be single car unless they cross the divider.

Whenever I see it happen I usually double my following distance and let all the idiots sort it out but most people just tend to put themselves in a position where they don't have an exit if something goes wrong.