Well, as someone who actually plays D3 here (and similar games such as Path of Exile), I can say this post is actually accurate.
I'm not sure why people have (and probably always will) have difficulty in understanding the concept here. Assuming you are using a resource spending build, which any decent endgame build is, if you are out of resource, your DPS stops. Attack speed accelerates this process because you burn through your resources faster. Often faster than you can generate in the time that it takes you to spend them.
In general, it doesn't matter about on-weapon procs, ability co-efficients or even what spell you are casting. If you have NO RESOURCE to cast ANYTHING your DPS is NULL!! Remove some attack speed and you will likely do less burst damage but more in the long run. Maintaining good, consistent damage in games like D3 is all about normalisation.