True, but in many cases you can still offer a service for free without ads. E.g. offer a free version with limited functionality, and then offer a paid version

True, but in many cases you can still offer a service for free without ads. E.g. offer a free version with limited functionality, and then offer a paid version with features that are needed mainly by people who use your product for work. Even if ads weren't an option, it's still advantageous to get lots of people using your product, and I think companies will continue to find ways to do so.