Some people will get a tarball ahead of the release; people that I have promised advance copies to, people that are good at breaking fedi software, people that can spot bugs in cryptographic protocols. A week or two ago, there was a bug in the P2P code that flooded all the nodes (handling of hallucinated block IDs had to be adjusted after the queuing system was replaced with just two tiers): I could turn them all off and revert them and debug, I knew what triggered it (because it had to be something I did), it only swamped my machines, I didn't have to try to get anyone else's logs or decipher their bug reports, and it didn't result in a major catastrophe that crippled the network because the network is tiny. It was a regular bug instead of an emergency. If this happened to a thousand nodes, that might be a real problem, but it only happened to a dozen, most of which are in my house. (I figure advance copies will probably get leaked but hopefully if/when that occurs, it's slow enough to catch big problems before they are huge problems.)