It means owning the code and the data. With webapps, the code and data are hosted and owned, the users do not own the code, cannot run it independently. This is a clear dileneation between owner and user, and the owners can use that clear line to create artificial scarcity of various kinds. (The most popular being the subscription SaaS model). It's also easier to defend your IP since end users never see your binaries.

> I like to make my software single html files whenever possible. People can just save them and run them locally. Havent met anyone who cares yet though.

I like that idea a lot, and I care. I think others care, but yes, it's a niche interest. Take a look at https://tiddlywiki.com/ for an example of a fairly successful project that uses the single html format running locally. However it suffers from limitations on File|Save which often requires a separate runtime of some kind to support.

Another project that approaches this ideal is https://redbean.dev/, @jart's tiny, performant, featureful single-file webserver. In this case the "single file" is a server executable + zip whose state must be updated on the command-line, but I think hits a sweet spot in terms of practicality, and a global minima when it comes to minimizing dependencies. (Redbean bundles SQLite and Lua so it's also possible to do through-the-web state updates as in a traditional webapp.)

My own project, Simpatico, aspires to be something along these lines.