The desktop computer came into being without local networks, let alone the Internet. What we're coming to now is a computing world where it doesn't matter much what platform you're using; networks are TCP/IP, files are increasingly in formats based on open standards, and applications can and often do run on servers with a platform-agnostic browser as the user interface.
The question is whether this sort of open exchange would have come about sooner if DOS/Windows had not become a de facto standard -- if we had IBM PCs, Macs, Amigas, and maybe even OS/2 boxes. Probably not.
Cheap commodity hardware running Windows was the Model T of the Internet. It's easy to write flowery, nostalgic odes to the Model T which was, let's face it, it was a pretty crappy car. But it opened the road to millions of people who would go on to get something more reliable, more powerful and infinitely more comfortable.
You could make the argument that if DOS hadn't become the standard, something else would have. That's likely true, but without the might of IBM behind it, it would have taken a lot longer for computers to become inexpensive and attractive enough to get into people's homes. In a world without IBM PC clones, we might be talking about the Mac as an alternative to the Amiga; Commodore had the biggest installed base in homes when DOS and the Mac entered that market.
At any rate, for all the moaning about how much better the Apple closed hardware model is for the individual end user, no one will argue it would have been better for the industry if Microsoft had adopted it.
Even the open source hobbyist software development benefitted from the explosion of hardware inventors, innovators and manufacturers that suddenly had a wide open market for their ideas and products. You could pick up a used commodity PC at a yard sale that originally shipped with Windows, wipe it, install your preferred flavor of Linux and be off an running.