Free software typically doesn't force you to share changes either, as long as you don't distribute the binaries. Patching GPL code and using it in a web application without ever releasing the source is perfectly fine.

The Affero GPL was designed to force the release of source even in that case. That's the only license I know which has that property though.

Free software != GPL. One could argue that the Affero GPL represents a continuation of the ideals which gave birth to the GPL, now that more and more applications have moved to being network services (something less common in 80's).