I've tried it before...people don't simply want to pay for mockups and vendors don't want to waste time developing them for free (in the hope that they may win the business).
I think the OP rightfully addresses a deeper issue at stake here - "I have no vested interest in the outcomes of any of the projects and I wish them best of luck." Or perhaps more aptly put - stop trying to cater to these people, it's a waste of your time.
The world is full of people thinking that what people like Gates, Zuckerberg, etc. have accomplished is both simple and repeatable.
If you build an app for yourself you probably have the requirements and wireframes welded into your brain since it's likely being developed to solve a problem that you encounter on a daily basis such as managing your dotfiles between all of your VPS instances.
When you're developing something to solve a problem you could never even imagine having, say wardrobe management software for the wife of a senior politician you're probably going to need those wireframes.
> If you're willing to work more closely with your developers, and you're a cool person, you can skip wireframes altogether.
Totally agree, but it's so rare to find a client-agency relationship like that in the web dev space.
> Ever build an app for yourself? Did you wireframe it? I bet you didn't.
Yes, I have built an app for myself. I've definitely wireframed it. I usually go through a crapload of wireframes, HTML mockups, etc. It's incredibly difficult (for me) to just develop without at least a starting point either written or in my mind.