Context:
Permissive licenses (commonly referred to as "cuck licenses") like the MIT license allow others to modify your software and release it under an unfree license. Copyleft licenses (like the Gnu General Public License) mandate that all derivative works remain free.
Andrew Tanenbaum developed MINIX, a modular operating system kernel. Intel went ahead and used it to build Management Engine, arguably one of the most widespread and invasive pieces of malware in the world, without even as much as telling him. There's nothing Tanenbaum could do, since the MIT license allows this.
Erik Andersen is one of the developers of Busybox, a minimal implementation of that's suited for embedded systems. Many companies tried to steal his code and distribute it with their unfree products, but since it's protected under the GPL, Busybox developers were able to sue them and gain some money in the process.
Interestingly enough, Tanenbaum doesn't seem to mind what intel did. But there are some examples out there of people regretting releasing their work under a permissive license.
The MIT license guarantees that businesses will use it because it's free and they don't have to think about releasing code or hiding their copyright infringement. The developers I've seen using that license, or at least those who put some thought into it, did do because they want companies to use it and therefore boost their credibility through use and bug reports, etc. They knowingly did free work for a bunch of companies as a way to build their CV, basically. Like your very own self-imposed unpaid internship.
The GPL license is also good for developers, as they know they can work on a substantial project and have some protections against others creating closed derived works off of it. It's just a bit more difficult to get enterprise buy-in, which is not a bad thing for many projects.
All my own OSS stuff I always release MIT licensed because I want to be able to use the libraries in my closed source job.
If you're the copyright holder, nothing stops you from releasing your work under more than once license. It is not necessary to use permissive licensing; you are perfectly free to release your stuff to the general public with a copyleft license while also granting your company a separate license even with proprietary terms if you want.
Only until you have any other contributor, as you're then no longer the sole copyright holder. If you still want to work like that you'll need a CLA.
Sure, but I was taking "all my own OSS stuff" at face value.
Correct me if I'm wrong but if I start a project with a GPL and a custom proprietary license for use at work wouldn't that also apply to any contributions by 3rd parties later on to that projevt? Afaik only adding or switching licenses with existing 3rd party contributions is difficult without a CLA.
Kinda. IANAL, but here's my understanding: If you're explicitly dual-licensing and publish the proprietary license then contributions can be assumed to also follow the same dual licensing. You'd need to be extremely careful with writing the proprietary license though, since your business is now using non-employee proprietary code.
If you write "the copyright holder may choose to allow an entity to use this work", then you do actually need permission from every contributor. If you write "this work may be copied, modified and redistributed freely by Blah enterprises" now the business cannot be sold without losing access (or possibly have it's name changed). If you write "Neshura may freely copy, modify and redistribute this" then you can't be fired or move jobs without the company losing access.
You can also never ever change this license, since every contributor needs to agree. So if a mistake is made when writing it you're just fucked.
On the other hand with a CLA that transfers copyright ownership you don't need to dual-license at all since everything already belongs to the business. Much less risky.