It's true — but advertising has two sides. You can of course be running a campaign that you're hoping for immediate ROI on, like a flash sale. In that case, you really want clicks and some sort of immediate indicator that the campaign is working, like conversions.
But sometimes as a business owner you're also campaigning for visibility / mindshare. At the minimum you want to distribute a message and let people know you exist. That's why people still buy billboards. It's a type of advertising that will probably never go away - especially because it's relatively low cost to implement for all sides - just need a designer to create the ad and you're good to go.
It doesn't seem like the most dependable business model but it's pretty timeless even in the digital age. The advertiser has an ego and instinct and is ultimately going to buy what they feel is going to work for their business.
This is of course true, and kinda obvious, but I am not sure this is workable as business model. I mean, here are not a lot of ads that are immediately relevant for me. Maybe once or twice per month there's something that I buy that ad could sway my decision at least potentially (i.e. expose me to some provider I wasn't aware of, or some brand I haven't considered). The rest is basically wasted on me. How much 2 clicks per month (with unknown conversion rate) are worth to advertisers? I have no idea, but I wonder whether it is possible to support a site on that revenue?
I, of course, could be wildly atypical case (for one, I use adblockers and rarely impulse-buy) and maybe typical visitor would be much more engaged with ads.
Or it could be that ad buyer industry (not ones that make the ads, but ones that order them - Fords and Chevys of the world) do not have proper tools to see how effective their ads are and just throw a chunk of budget to the wind, get some traffic from it and feel good about it.