Antenna theory

Sorry just in case im failing to understand this. Is this description explaining the transmit pattern or is it describing Rx?

The debate we are having is how a 10dbi antenna can witness/hear more than a 4dbi antenna and the usually answer comes down to its Rx.

But most of us believed when the antenna wasn’t sending/beaconing it was inactive and in order for my antenna to witness another beacon their beacon had to reach my antenna in full. Which then makes me wonder where the Rx comes into play as surely it then just comes down to whether or not the sending beacon can reach me or not regardless of what my Rx is.