It's not "getting" out of hand. This exact mass personalized campaign style has been around since before the Internet.

I managed IT at a printing press where we used letterpress printing on cotton rag paper to "type" "personal" letters to lists of a million people. We "signed" the letters in different ink. We paid extra for first class stamps instead of postage meter.

And, we would send up to five letters in a series each referring to the one before, and by the last letter, we printed yellow highlighter over key sell phrases and 'wrote' in the margins with different colored ink to say this is the stuff that really matters to you.

These campaigns were deadly effective.