Your last sentence is intriguing. Do you believe that ads are the only means to keep services "free" or "cheaper"?
If you do, then that would explain why you have come to accept them as "necessary" for services to be "free" or "cheap". (i.e., you've made a causal link between ads and "free/cheap")
If you don't, then I have more questions for you to answer.
OK, so why can't ads be optional then? If you want the benefits, then you just "turn on" ads (=helpful suggestions).
If ads are beneficial why would they charge you extra to turn them "off"? Under your reasoning, we should be paying extra to see ads, because we'd get helpful suggestions.
How can I convince young programmers who read StackExchange and generally look to forums for "advice" that it is worth their time to learn ANSI C (e.g., because it performs better than their suggested alternatives, it is time-tested, more widely known among programmers, etc., etc.)?
If you do, then that would explain why you have come to accept them as "necessary" for services to be "free" or "cheap". (i.e., you've made a causal link between ads and "free/cheap")
If you don't, then I have more questions for you to answer.