Hi HN,
Vincent here, maker of Streamline 4.0. I spent the past 12 years perfecting icons and making the largest sets on the internet.
The 5 open-source sets are:
1. User Interface Icon Set (1,000 icons)
2. Streamline Flex (500 icons)
3. Streamline Flat (500 icons)
4. Covid Icons (147 icons)
5. Nasty Icons (45 icons)
I also dislike this is promoted as an open source icon set. This is a commercial product providing free samples. By design, it has a funnel of free / 'open source' users of which some will be turned into customers.
Finally, it's amazing to me as a programmer how commercial minded designers are in tech. It would never occur to me to create a programming library where you have the 'basic' open source version and the 'optimized' commercial version. But basically this is how graphics / icons / page templates / etc are being marketed.
I guess this is where any kind of 'community' helps. If a library has a community, it would be forked the 2nd day if it tries to pull something like this. But icons / templates / graphics are generally the work of a single person or small group of persons. There is no community that may philosophically decide they disagree and thus fork the project on new license terms.
All in all, quite depressing. But, I understand, we all need to eat.