I like AGPL in theory, but in practice it never works like that. They are protected by a smoke screen — you don’t know if they are using something, how they are using it, or what they’ve built on it — and even if something did leak about their usage they are protected by money — the vast majority of FOSS projects won’t have the resources to pursue any kind of legal enforcement or reasonable remedy. In practice, they will use and build on A/GPL software while contributing nothing back in blatant violation of the spirit and intent of the license, because who is going to find out or enforce it?