Almost everyone does - not doing so is against the grain. Having that extra week to do rotations on feedback means proper investigative journalists and analysts can dig into detail, ask relevant architecture or market related questions and wrap it up rather than discuss bits in news stories across a week when everyone is spouting conjecture.
By prebriefing everyone early, it gives a chance to get stories correct first time without assumptions. Typically there is a narrative to weave, and it's the PRs job to communicate that to the press in such a way that they understand it (of course, they might spout BS and it's up to the journalists you trust to recognize when it is, through deep understanding). Nevertheless, most of what you read is typically copypaste of press releases, which is why it is important to track journalists you know will dive in.
Intel does, AMD does, NVIDIA does, ASUS does, etc. Very rarely is a halo product launched without media prebrief (either on location or conference call over the phone).
Most people in the smartphone industry do as well - Apple and Samsung are actually the big exceptions.