Sounds like you are willing to work with merging traffic. I'm not. Let me make that real clear so there is no misunderstanding. If I have room to move over without having to accelerate, brake or take it from cruise control I will. But if moving over is not an option. I am not braking, accelerating or taking it out of cruise control. Paint me as discourteous if you like, but I have reasons for my position on this.
First, I have to consider the people behind me if I intend to brake. What right do I have to inconvenience them? If there is nobody behind me then it is the responsibility of the merging traffic to recognize that once I am past they have the road to themselves. Since I don't know what the merging traffic is going to do it is foolish and maybe dangerous for me to adjust my speed. I have the the right of way and as long as my speed is constant the merging traffic can do what they deem necessary to accelerate to get in front of me or to delay acceleration to fall in behind. If we are both speeding up or slowing down then neither of us knows what the other is doing.
I will always try to anticipate how I am going to deal with merging truck traffic. Unlike in a car the operator cannot stand on the accelerator and see changes in the rate of acceleration. So if a truck is merging I am scanning my mirrors to determine the best course of action for us both. Sometimes a merging truck can be accomodated, sometimes not. But I will not grossly change speeds to help merging truck traffic unless it is the only option. The merging traffic has to yield. We on the right of way have no obligation.
You cannot help people who have no clue about merging. They are terminally stupid and if you think you are being a nice guy by trying to help them you haven't taught them how to fish, you have only fed them for the day. They outnumber you. And right now I think the stupid ones are winning.