You think advertising is 'evil'?
How far do you take that? For example does a listing in a local newspaper advertising a law cutting service count as evil? Is any form of telling people that you off a product or service really an act of evil?
Maybe they do, but using the idiom “necessary evil” doesn’t make it certain that they do. Probably nearly nothing colloquially described as a “necessary evil” is actually “evil”. It can be only a pain or an annoyance, but required.
>[…] the use of the term "evil" in the phrase does not necessarily indicate that the thing being characterized as a "necessary evil" is something that is generally considered an "evil" in the sense of being immoral or the enemy of the good.
I'm not saying that all advertising is bad either, it's the specific case of B2C online advertising that compromises privacy and massively reduces the signal:noise ratio of the platform you're using. Sales and marketing aren't inherently bad in themselves, obviously.