This is about FOSS and I can't see that Audiotool is FOSS, and Samplers are not Sample Libraries. Sample Libraries are ubiquitous among producers who want a good sounding recreation of a real instrument but cannot afford (or morally support), for example, Pianoteq's modelling algorithms or Spitfire's premium libraries, neither of which are FOSS, or the instrument itself or a session player.

As I said, the most promising multi-sampler or sample library software with an active community was Decent Sampler, which isn't open-source and now supports DRM.