Not really. GPLv3 will prevent hardware manufacturers from locking down their devices if they intend to ship Ubuntu Mobile. This is a good thing for users of those devices. I can't defend Canonical's support of proprietary drivers, especially on these devices that are known to be used for such pervasive spying, but at least a non-hardware-locked device allows for workarounds (i.e. deployment of your own free drivers).
I'm sorry, but must be missing something. How does a GPLv3 display server prevent locking down the hardware? Afaik, the anti-TiVoization stuff only applies to the software that's GPLv3, not the stack it's running on.
Can you point me towards some people arguing this? It's patently false. If it were true, every single application on your typical GNU/Linux box would also be GPL.