In reality, electromagnetic field propagation is extremely complex. Everything in the earth influences the recorded electromagnetic response, from the highly resistive air to the most seemingly insignificant conductive brine filled sandstone unit. Everybody has a preferred method to understanding electromagnetic field behaviour. It could be mathematically, rules of thumb or with static field lines. I like the idea of streamlines as they are able to visualise simulated electric, magnetic and Poynting vector field lines in time. Each to their own.