Netflix and streaming services don't really offer this because while other people may have watched what you're currently watching, your viewing experiences aren't synced up. You can watch whatever you want when you want and so the chances that you're watching the same thing at the same time, synced with others, is very small. Though freedom of choice is the major strength of streaming services and I love them for it, you lose that vague connection of sharing a singlular experience - watching that show, at that time - with thousands of others.
Maybe if Netflix were to implement a feature that indicated how many people were watching a show or movie at any given time it'd restore the communal aspect.