Sending Pi 5s to people who're going to review them before the release makes sense, but of course it'd have been nice if they sent them to people who contribute important pieces of the ecosystem, too.
They do this, but not to all corners... a couple in the retro game dev scene had alpha boards, some Linux devs, and especially many of the companies who build SBC accessories. There's no public list, but Raspberry Pi seems to distribute pre-release hardware fairly widely, and collaborates with a decent sized community of 'builders' who can help iron out bugs or get time in to test weird edge cases.
I think after the USB-C debacle [1] with the original Pi 4 launch, they decided to widen the net a little (with the CM4, Zero 2 W, Pico, etc.). "With many eyes bugs are shallow" and all that jazz.
https://github.com/pftf/RPi4
Sending Pi 5s to people who're going to review them before the release makes sense, but of course it'd have been nice if they sent them to people who contribute important pieces of the ecosystem, too.