So you consider Thiels and Apogees monsters, Erik? Feed them properly and behold the magic...
Amplifier eating monsters, yes, absolutely. Please read my replies in the context of the OP’s question about misfits. It is not meant to attack your personal speaker/amp choices.
The impedance curves are designed not to be deliberately/unnecessarily difficult, but to deliver the sound character, and especially the bass response, that the designer intended.
This is not always the case, and I was referring to exceptions.
In the case of the Apogees, you are correct. They are purely ressistive and require the current to work against the magnetic force. In the case of ESL’s there is no helping that the entire construction is a giant capacitor. You cannot avoid the impedance dropping as frequency goes up. So, these are both misfits, and the term "monster" doesn't mean ugly or unwanted, but difficult to drive adequately, pretty much as your post to me mentions.
In the case of the specific Focal speakers I analyzed it was a deliberate choice in crossover design. That is not to condemn all Focal speakers, but it was interesting that in many of the reviews for that speaker reviewers commented on how easy it was to hear differences in amplifiers.