I'm no stranger to the GPL. I had a project which spent 9 months arguing with legal in a large institution to support 6 months work involving an independent ope

I'm no stranger to the GPL. I had a project which spent 9 months arguing with legal in a large institution to support 6 months work involving an independent open source contractor to work on a GPL'd thing. But it is a restrictive license. Its "plague"-ness comes from its incompatibility with other licenses. Or at least, in the case of ZoL/CDDL and Linux/GPL, the crippling practical realities of the resulting kernel module binaries that are a derived work trying to impose restrictions on each other. That's why you can find precompiled modules on the ZoL website, but never in a distro. That's a legitimate criticism, but as you say, also its defining feature.