The copyleft licenses are toxic for adoption. Companies default away from them because there are a lot of murky unknowns (e.g. if you run a copyleft service and connect to it via API, is that extending it? Does that service’s source have to be shared?) that simply aren’t worth the hassle.

If you want your library to get traction with many real world use cases, you need to have a permissive license. If you want to stick to the principles, you’re going to sacrifice adoption.

Not saying one is better than the other, but there’s a tradeoff.