If your goal is sticking it to the man and demolishing capitalism or whatever then it's different of course.
(I guess in many ways this is a data point to support the “OSS work becomes just a source of free labor for large tech companies” thesis up thread.)
No one at any company I've heard of or been involved with cares if you simply use, i.e. run, Linux or other GPL software. That doesn't affect the licensing of your own software.
What they do care about is if you take the GPL software and incorporate it into your own product.
Often we are the end users. Because of permissive licensing phones, routers, iot devices have a lot of closed or otherwise locked own components that I cannot trust nor modify.
The same apply to SaaS.
Copyleft, having to release code diffs, is a stipulation / restriction.
MIT/BSD is the one without any stipulations / restrictions:
* https://en.wikipedia.org/wiki/MIT_License
Depending on one's goals one may be better than the other.
> My work on free software is motivated by an idealistic goal: spreading freedom and cooperation. I want to encourage free software to spread, replacing proprietary software that forbids cooperation, and thus make our society better. [1]
Free as in freedom for the users of the software to control, audit, and modify what runs on their hardware.
The stipulations are there to prevent people who aren't aligned with those goals from benefiting from (and working against) the work done by the community that believes in those goals.
It's easy to give the lie to this, because the restriction they are unhappy with is the restriction against restricting others. Anyone complaining about that is just masking a demand of "free for me, but not for thee" - definitely _not_ "totally unrestricted."
For Stallman, and the rest of us inspired by the copyleft movement, writing GPL software wasn't merely a way to impact the profits of capitalists. He would have been scarcely more satisfied with closed-source software written by a democratically organized cooperative and released for free. The goal was and is to ensure that users have the freedom to know what the code running on their machines is doing, and to alter its behavior if they wish.
That dream seems so distant today that people worry it may never be satisfied, but I have a more optimistic view. Someday, hardware generations will not be so rapid or represent such major improvements. That will create an opportunity for the GPL ecosystem to close the gap in functionality and provide alternatives that run on the hardware most people own. Mostly, the GNU project is always running behind on the hardware treadmill; keeping up with software functionality is easy by comparison.