I too would prefer it if every professional had the same moral compass you and I have; but that is a separate issue. Hence why people can be both successful and arguably immoral.
Granted, modern marketing is rarely applied this way so in practice almost all marketing is dishonest, but that's not what "by definition" means.
Marketing is dishonest "by definition", because its purpose is to persuade, not inform.
Really the question is - whose interest are you purporting to serve by communicating with me? Yours, or mine? And whose interest are you actually serving?
which I think is quite reasonable.
it's the stuff people do and call it marketing and advertising that is dishonest - trying to make people want something despite it not being in their best interest.
once upon a time, I think we trusted businesses because we saw most business was honest. and now much less so, since we see most business is dishonest now.