I would also like to agree that Signet should be a BIP.
Problem: Testnet is unreliable. *Testnet is used often for development of Bitcoin*.
Proposal: To improve the dev environment for Bitcoin, let's create a new kind of testnet that is more reliable.
I would also like to hear the logic behind "Testnet is Bitcoin" but "Signet is not Bitcoin"... both are not 100% compatible with mainnet consensus processes.
-Jon