Comment by vanderZwan

Like the other comment said: the point is live streaming, so the encoding has to be done in real-time. Being the slower of the two steps (assuming comparable hardware between sender and recipient), it becomes the performance bottleneck when measured as frames per second.

When measured in, say, total sum of all CPU cycles and hence total energy spent, then yes: the decoder is the bigger deal. So your argument holds for non-live videos.