GPL, BSD, and NetBSD - why the GPL rocketed Linux to success

The piece below is an interesting perspective as to how the GPL sent Linux into orbit. Seriously, you should read this.

Charles M. Hannum (one of the 4 originators of NetBSD) has posted a sad article about serious problems in the NetBSD project, saying “the NetBSD Project has stagnated to the point of irrelevance.” You can see the article or an LWN article about it.
There are still active FreeBSD and OpenBSD communities, and there’s much positive to say about FreeBSD and OpenBSD. I use them occasionally, and I always welcome a chance to talk to their developers - they’re sharp folks. Perhaps NetBSD will partly revive. But systems based on the Linux kernel (”Linux”) absolutely stomp the *BSDs (FreeBSD, OpenBSD, and NetBSD) in market share. And Linux-based systems will continue to stomp on the *BSDs into the foreseeable future.
I think there is one primary reason Linux-based systems completely dominate the *BSDs’ market share - Linux uses the protective GPL license, and the *BSDs use the permissive (”BSD-style”) licenses. The BSD license has been a lot of trouble for all the *BSDs, even though they keep protesting that it’s good for them. But look what happens. Every few years, for many years, someone has said, “Let’s start a company based on this BSD code!” BSD/OS in particular comes to mind, but Sun (SunOS) and others have done the same. They pull the *BSD code in, and some of the best BSD developers, and write a proprietary derivative. But as a proprietary vendor, their fork becomes expensive to self-maintain, and eventually the company founders or loses interest in that codebase (BSD/OS is gone; Sun switched to Solaris). All that company work is then lost forever, and good developers were sucked away during that period. Repeat, repeat, repeat. That’s enough by itself to explain why the BSDs don’t maintain the pace of Linux kernel development. But wait - it gets worse…. Source: dwheeler.com