At least? So the person already selflessly donated an open source library to the world, even if only usable if you comply with certain terms, and that's not enough? I frankly don't get this perspective at all.

Why not only let other people use it in their products, if they make their code available on the same basis as I released mine?

Code in itself isn't useful. You're not improving the world by writing code. You're improving the world with the impact that code can have and the value it can deliver.

But don't forget the LGPL, which lets GPL code to be used even inside proprietary one.

It may improve the world. From my perspective code that is built to extract value eventually attempts vendor lockin to create a long term revenue stream.

That is one freedom I support.