Board Thread:Boruto Discussions/@comment-1018594-20161222205643/@comment-25122992-20161225225700

Well, I think there's a significant difference between regular Rinnegan absorption and the absorption Momoshiki utilised. The first one, known as Preta Path, could absorb the chakra on touch, as well as the techniques, via Blocking Technique Absorption Seal. The problem is that technically you have to touch the person/technique to suck chakra in, while Sasuke was immobilised and thus unable to touch the shadow on the ground. Momoshiki's absorption is seemingly able to suck chakra and techniques in without the need of directly touching them, it's just enough to have them nearby.

However, I must admit that it doesn't exuse Sasuke's inability to absorb ninjutsu Momoshiki was constantly throwing at him and the other opponents, especially on the chunin exam arena.