Many open source licenses levy restrictions upon the acceptable use of the software. Those restrictions may include attribution requirements, up to and including a requirement to include the license when redistributing the code; they may forbid using derivative works for commercial purposes; they may require the downstream project to utilize the same license. Open source is not the same thing as "anybody can do anything they want forever."
Yup, if we take OSI as defacto authority on open source definition
> 6. No Discrimination Against Fields of Endeavor
> The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.
Well, if it's my memory at fault then I apologize. My memory of the comment I replied to didn't include the initial qualifying phrase with either word choice.
Copyright violation is not theft. Your effort to create something that can be effortlessly copied conveys to you no property. Society deems it beneficial to grant a time limited monopoly on copying it to spur innovation.
Stealing a car - or anything tangible - means... the owner is very literally deprived of the benefits of owning said car/thing. Can't really say the same for a copied pattern of bits.
Copyleft is still a thing. Right to attribution is still a thing. Please, read about it and you will discover that there is a lot of nuance to the open-source code.