> If instead you mean "figure out after some period of implementation whether the standard itself is good", I don't know how that's meant to be workable.
The forcing function can potentially be: this final draft is the heir apparent. If nothing serious comes up in the next 6 months, it will be summarily finalized.
It’s possible this won’t get any of the implementers off their ass on a reasonable timeframe - this happens with web standards all the time. It’s also possible that this is very unlikely to uncover anything not already uncovered. Like I said, I’m not totally convinced that in this specific field it makes sense. But your arguments against it are fully general against this kind of phased process at all, and I think it has empirically improved recent W3C and IETF standards (including QUIC and HTTP2/3) a lot compared to the previous method.