I don't think that's true at all. You absolutely can and should build an MVP of all these things. You certainly could release an MVP search engine (or even a browser-based game). You probably can't hope to gain traction at large with an MVP browser or operating system, but you can start using these things internally and dogfooding them.
IMO, iterative development isn't necessarily about releasing something fast to the public, it's about rapidly building a working version that you can interact with, test properly as a whole working system and show people, so you can quickly figure out what are the most obvious issues to address and improvements to make. You can test this software internally, show it to your friends, have a small private beta or even hire testers depending on your project and budget.
This is in contrast to a more traditional/naive development model where the team isn't even trying to have a working/testable version, and instead focuses on spending weeks/months building components separately, which they hope will come together into some grand vision at the end. This approach is terrible because things likely won't come together seamlessly. The different components can fit together poorly, effort is wasted on features that weren't actually good ideas in hindsight, etc. Software projects developed this way are often late, overly complex and poorly designed.