Linux is not what you see and use when you install a distro. Linux doesn't have a web-browser built in, or a graphical environment, or even a console. In the end, Linux amounts to
one single file that your computer loads when it turns on.
Linux doesn't really change that much from distro to distro -- everything else does. Mostly because you can only get some things at the expense of others. A wonderful system for programmers would by necessity be very tedious for casual users, while a wonderful system for home-users would, by necessity take quite a bit of control away from an experimenter.
And take something completely alien like OpenWRT. It's a linux distro that runs on
wireless routers! That pretty much has to be a its own distro.