The thread has morphed into a lot of posters giving their own scenarios. The gist of it as I understand it is this- the driver is in the right lane and basically boxed in in heavy traffic. A car is attempting to merge onto the freeway by riding side saddle next to the op's vehicle. In this situation I'm inclined to make the merging vehicle adjust their speed rather than the vehicles beside me and behind me. Yes, it is the law and yes, it makes better sense to have one car maneuever than 3 or more.
There is also the issue of the ignorance many drivers have over the procedures for merging into traffic. That could be helped on a state level with some PS announcements and some signage on the roads. Whether due to age or inexperience, or they are just used to seeing traffic move over for merging vehicles, they think that is what you are supposed to do. Just as the driver that jockeys for a spot in front of you, then slows down abruptly for the red light, they do not care or realize that a truck/trailer combination can't stop or go or switch lanes like their passenger car does.