Strong +1.
Yes, absolutely. When trying to build executable targets with SwiftPM using @main, I found this limitation incredibly frustrating.
Yes, it resolves the long-standing lack of clarity in product and target declarations. The fact that one could declare implicitly executable targets without declaring a corresponding product was a source of confusion for me, and required additional heuristics to be added in developer tools that I work on. The solution seems explicit enough, but not too verbose. It also brings Swift forward on other platforms, as the possibility to use @main is sorely missed on non-Apple platforms.
N/A
In addition to reading the proposal, I was closely following the previous discussions and the pitch of this proposal.