If someone speeds up when they see a car in another lane signalling that they are going to merge, in order to prevent that car from safely merging, when the merge would have been safe to perform had they not sped up to prevent it, they are definitely driving incorrectly.

You are misunderstanding. Please re-read what I've written so far. At no point did I suggest what you are saying.

> This is how you're supposed to merge. When you get on the freeway you don't expect the current flow of traffic to accommodate for you, instead you accommodate for them.

Specifically, you should read the rest of the line you are replying to here.

I mentioned people behind me speeding up to make it impossible for me to merge without braking, after I signal. At no point did I say they should "stop" or "slow down".

I was pointing out that people deliberately speeding up to make it harder to merge without braking are causing problems. It was a light-hearted comment about the failure of many drivers in my town to properly zipper merge.

Here is a video demonstration of zipper merge to help you better understand appropriate driving behavior: https://www.youtube.com/watch?v=cX0I8OdK7Tk