The general trend for contemporary sample libraries is to keep adding more velocity layers, more round-robin alternating samples, and more articulations accessible by keyswitches. While this formula for expansion results in larger, more extensive libraries, it is still an extension of traditional sampling, maintaining many of the same foundational limitations which prevent sample libraries from crossing the "uncanny valley". Essentially, it's what keeps the libraries from overcoming what defines whether something sounds real or sampled: context.
Context is what connects samples, relating one articulation to the other, in order to build a cohesive perception of the instrument being not a collection of articulations played one after another, but a complete performance. It's like composing a song by sticking together a series of elaborate chords. Without paying attention to their overall harmonic function and progression, the chords will sound disembodied. While they might sound great on their own, there's a lack of connection. So in the sense of sampling, single articulations only serve the overall context of the instrument, and therefore cannot be solely relied on for providing realism.
In order to convey realism, the humanistic characteristics of the instrument must be artistically outlined. Capturing details is irrelevant if fundamental qualities are unrealistic. In other words, if all the effort is put into the details, without actually stepping back to observe how these details affect the overall perception of realism, the result is a creation that focuses on technicalities rather than form and proportion.
Of course, sampling lots of articulations is not a bad thing. In fact, many times it is necessary to sample a large amount of sampling in order to properly convey the breadth of sounds the instrument is capable of playing. However, without a central intelligence (for example, a KONTAKT script) controlling how the articulations are played within the musical phrase, the realism of the virtual instrument will not be able to cross the uncanny valley.