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.
No, it isn't; a client talking to an AGPLv3 service over a network API stays a separate program and is not touched by the license at all. Section 13 places obligations solely on whoever runs a modified version of the service, while remote users, API clients included, only gain the right to receive that service's source. So nothing on the client side must suddenly become AGPLv3, and the only thing that ever has to be shared is the AGPL'd program itself, not anything across the API boundary. The first half of your post is basically unfounded FUD; the second half tracks.