So here's my take, GPL is pretty much the de facto choice for full open source applications, and here it makes much sense as it's a 'finished' product, and in many cases the individual parts of that finished product which are reusable are licenced permissively.
Meanwhile components like libraries, frameworks, have since long leaned towards permissive or atleast LGPL style licencing due to them constituting only a small part of whatever program they are used in.
Like the edited article states, the author was wrong in saying GPL is declining or that projects are in any way switching, the thing is that these days we see lots of new open source developments in web technology frameworks and these frameworks are predominantly permissively licenced as they are basically components on which full web solutions are built.
And given the sheer number of web oriented open source tech popping up these days it's no wonder we are seeing new permissively licenced code dwarfing new GPL licenced code these days. For example when I viewed the 'Popular Watched Repositories' list on github, the only ones I know are GPL licenced were Linux and Git, and the list was heavily dominated by web targeted projects.
Now there seems to be a strong anti-GPL sentiment in web dev, which is likely due to people working there relying heavily on open source components for their proprietary solutions and as such they simply can't use GPL, hence complaints.
Bottom line is that there is no 'one type fits all' licence, which is why we have licence proliferation. I've always held the belief that whatever the author chooses is the right option, be it permissive, GPL or even keeping it proprietary.