Yeah, probably. But the presence of packages like GNU libc can make it harder for the manufacturer to lock the device.
> ... kernel version due to proprietary binary blobs which nearly every phone uses.
Sadly, binary blobs are always an issue. In the case of Linux, this happened because many Linux developers don't care about binary blobs. If they did, you won't see any binary blobs (as it is a violation of GNU GPL).
> ... with complete open source drivers
My main point was to quote that 'open source' doesn't solve these issues. We should take software freedom more seriously.
> ... (or a GPLv3 kernel).
I wish we will not have to wait until the human civilization end in fire to see this.