It's the people who hit the gas when they see your signal, that really irk me. In Austin I stopped signaling because it was a punished behavior.

My experience driving in MA and NY was similar, but so often it was because a rusted out shitbox was trying to merge in that would slow down traffic significantly, and not only put me at risk of rear ending them, but being rear ended myself.

When flows merge, there's turbulence. There's less turbulence if the flows are more closely matched, including speed.