It's a question of motivations. Linus likely believes in the benefits of collaborative development, and that the GPLv2 creates a legal framework to allow for t

It's a question of motivations. Linus likely believes in the benefits of collaborative development, and that the GPLv2 creates a legal framework to allow for that development. However he also likely cares more about the software aspects (getting contributions to make better kernel versions and have them be widely used) than the more philosophical aspects of software freedom. The philosophy on binary drivers for example is one where the Linux kernel does not guarantee a stable binary interface - it isn't that you can't legally distribute a binary driver (with caveats), but he has stated he would like those developers to occasionally "wake up in a cold sweat" over their linux binary drivers breaking on minor releases. Additionally - because of the velocity of the linux kernel, maintaining a substantial vendor fork is not simple. This creates an atmosphere where maintaining functionality outside the mainline kernel could be a technical/financial burden that justifies any IPR release needed for a L-K contribution. The number of contributions also means that such forks are likely not a significant fractional contribution compared to the contributions which people are willing to make in the open. The success of the project no longer depends on enforcement of the publication clauses. Finally, clauses in the GPLv3 and AGPLv3 do influence and even force technology choices. The community likely does not want to lose contributions by pushing people to other kernels, and the commercial interests contributing to Linux would have to account for lost customers. AGPLv3 is often chosen by commercial entities to force distinct commercial licensing of a published-source code base, rather than an effort to protect a community of contributors. As none of the commercial interests in Linux have exclusive copyright assignment to do a non-AGPLv3 license, there is significantly less commercial benefit for them to support such a move.