Licensing and cost is similar to Qt (free for open source, $$$ for commercial applications, though I think JUCE is cheaper). So, at least relatively to Qt, it d

Licensing and cost is similar to Qt (free for open source, $$$ for commercial applications, though I think JUCE is cheaper). So, at least relatively to Qt, it doesn't particularly limit popularity. And even in an absolute sense, you can't confidently say that dual-licensing limits popularity in the long term. If JUCE and Qt were free for everyone, perhaps they wouldn't be able to have the full-time developers they both currently have. So maybe they wouldn't be as good, thereby decreasing popularity against competing dual-licensed libraries. This is all wild speculation, of course, but it's an example to show how their model works.