Dear Rabbi Simon
When we connect with one another for prayers in a virtual space (e.g. Zoom, Skype, etc.) and we can each see nine other men, why doesn’t it count as a valid minyan?
TY for your question. The answer is that in order to constitute a quorum (minyan), the 10 men have to be in the same space. 5 and 5 (or 9 and 1) even in two rooms in the same building is problematic. Even two sides of a street or thoroughfare is subject to dispute. However, if there are 10 men in a room and an 11th joins via Zoom, he may respond to kedusha, etc., and there are grounds to consider him to be praying with a minyan.
Rabbi Rashi Simon