This is very true, but only if it's obvious that some data is supposed to be sent to the server, e.g. a search box. In my mind this pattern didn't apply because it was clear something was supposed to happen on the client, not the server, i.e. activate the timer. I presumed that causing the text box to lose focus would activate it.

I know I'm wrong, I just described my dozy error caused by what I perceived to be an anti-pattern.