While Atmasphere is correct in saying that it is possible to achieve thermal compression in planar-magnetic drivers, in practical terms it really doesn’t happen much, at least not in larger drivers. Being involved with Analysis planar-ribbon speakers for almost 2 decades, I have witnessed some very informative testing. In one test the bass panel was subjected to considerable power at low frequencies to test thermal saturation and the mechanical integrity of the adhesives used. Even beyond its usable max excursion practically no heat was generated (short term). The very thin aluminum foil with considerable surface area is essentially self cooling. This test was extreme.
I would not call the planar foil a coil because it’s not, at least not in the case of the Analysis design.
Some compression occurs in planar drivers, including ESLs, because the membranes are stretched across a frame. The mechanical impedance is not linear. The greater the excursion the more power is needed. Analysis speakers address this mechanically induced compression by using a rubber surround. The design is quite effective in reducing compression. Other ways around this inherent quality is by using VERY large panels or subwoofers.
To the OP, I think people like what they like for a variety of reasons. Some people like large aluminum boxes with tons of power because they think they are cool, others like tube amp with exposed tubes because they think they are cool. Some people are fulfilling their audio dreams from a time before they had the money to buy their dream gear. There are valid arguments for high and low efficiency speakers. There are also trends.
Personally I lean toward high efficiency speakers. Our Apollo series OB line array speakers are high efficiency for several practical reasons, mainly because HE speakers always sound much more lively (linear dynamic contract) to me. Live music sounds lively. It’s one of the main elements that creates the experience. We will be showing our Apollo 9s at AXPONA using 300B amps if anyone wants to hear high efficiency OB line arrays.