Please take this suggestion, based from the view of a decision maker which framework to use:
I hear you saying: "Processwire can do everything. It is not limited to web sites."
Sure, it's true and we all got it. However, you canot target "everything". You have to market to specific demand.
The success of WP and Bootstrap is their totally overwhelming "out-of-the-box" instant gratification. Click.. Click.. AWESOME website. "Done!"
Of course, it is not done. However, users are hooked enough to dig deeper, study, try thing out, extend. And bam, they invested additional time and are captured in that ecosystem.
While the Processwire installation technically is flawless, it spits out newbies into the desert (or alternatively into nah sort of website template). The gap between the Processwire post-installation situation and something WP provides with their modern templates is too high.
We almost skipped Processwire, because we just didn't know how to get to a first success. It is only, that WP exploded after installing two incompatible plugins, that we came back.
We now work with a Processwire Pro to do the website for us but not everybody is willing to invest into the blind.
Processwire is totally awesome - I felt that with my very first look. It is so clean, fast, tight, professional, secure and flexible, that I want to see it thriving.
Please get users hooked with an awesome general startup experience, people can start working on. it doesn't take more than a beautiful modern website template and ideally with a page builder module preset.