I've never heard of this idea before. It horrifies me, because it says, "We don't trust your judgement."

In your shoes, I would definitely be open to including the client(s) in the drafting of the "Wanted" list of skills, experiences and talents.

But doing your work? That's what they're supposed to be paying you for.

And you're right, it would be so time-consuming nobody would ever get any work done.

I would check if this kind of thing is done in the defense industry; I'm not aware of it but it's the only place I can think it might happen.

"How am I creating value for you, then?" is the question I'd ask the prospective client if they pushed about this.