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.
That is actually a really bad rule, though you probably are only joking.
There are many examples of short, but very valuable code. Just think about anything math or physics related.
A totally new or even just a very efficient implementation of an already existing algorithm can be gigantic if others need to build upon it.
And many licenses are verbose not because they are complicated in intent, but merely because they need extensive legalese prose to cover against many possible avenues of attack.
No, I wasn't.
A rule of thumb is not a strict law. I never disputed that there are certain edge cases. What has to be considered but is not on the radar of most people: Threshold of originality. A "valuable" 3 LOC bash script is likely not being able to be copyrighted in the first place. In cases where the work is tedious but not creative, the work may also not be able to be copyrighted (depending on jurisdiction). See https://en.wikipedia.org/wiki/Sweat_of_the_brow whether a certain jurisdiction protects tedious work or not.