Turn signals - Statement of intent or request for permission?

In response to another recent question a LEO made a statement that basically suggested that merging “without permission” was a traffic violation.

Yes, I quite understand that the topic at hand was about pushing in line, and in that situation somebody must take action to let you in. However, in other driving situations such as merging into a moving traffic flow I notice that some take the turn signal as their queue to speed up to actively prevent one from changing lanes as though doing so is some sort of personal insult.

IMHO, a turn signal is a statement of intent, not a request for permission.

Opinions?