Earlier quoted context omitted.
It's not just fashion. It's a question of "Do I want someone to use my software?", because with GPL the answer would be no for a lot of projects.
Why do you think that? Linux is the most widely used operating system in the world and it's licensed under GPL. People don't choose not to use software because it's GPL. Why would they?
It takes a very forward-thinking person to understand that they have more to gain from the thousands of eyes and the support of the community, than from a paywall that gates access to their creation. (And that person could reasonably choose to license their software as GPL or any other open license, there are lots of trade-offs.)
But if you're not building the system from scratch, you need to be aware of the licenses you've accepted, and for many businesses the addition of GPL software to the stack will be a non-starter. Do you think we'd have Apple as it is today if it wasn't for BSD Unix and the BSD license?