Just like if at the grocery store, you could choose to pay or not pay. It would be totally okay not to pay. But if the number of non-paying customers grew too much, the owners would make it mandatory to pay. This did not happen to the web yet.
Not only is the foundation weak, but the advertisers themselves are really, really poor at actually delivering relevant advertising. If 25% of every ad that I saw led me to a product that made my life genuinely easier and/or more enjoyable, I wouldn't mind seeing them, would I? Instead I most prominently see ads for a product or service that I've just paid for, or their competition. Too late? With all the money being spent on marketing I'm disappointed they can't do better.
And worse still, there are people (and machines) flooding what was once a useful internet full of knowledge with worse copies of that knowledge, sometimes algorithmically scrambled and riddled with affiliate links. Too much information! Some good and some very bad. We're in a bad state, and advertising has a lot to do with it, in my opinion.
Or everybody would stop visiting corporate websites and we'd go back to the user-generated web of old, where people created stuff out of love, instead of to get views and sell ads.
Oh how I miss those days. Back then, the advertising industry literally scoffed at the idea of advertising on the "It's just a passing fad" early web [1], and most of the people online at that time were "content creators" of one kind or another, just looking to share what they were passionate about with others around the world.
[1] Source: I used to run a small printing business back in the day, and tried for years to convince advertisers of the value of advertising on the Internet and was literally laughed at…
it was never OK to never pay at a grocery store. But some stores don't want the cost of enforcement, so accept some losses from stealing.
Whether this argument applies to web based ads is difficult to say. I don't agree - but there's valid viewpoints out there do agree.