I totally agree on the pedantry stuff, and i think that it is really depending on what each person thinks about it. For me, a kind of Martial Art has a tradition, a specific form or style or is following certain rules. I believe that there is also some kind of beauty in those 'Arts'...
I personally would even go further and divide Martial Arts and Combat Sports
where I would put the traditional styles that have no competing aspect in it
(by that I mean competing man vs man for a championship bout, not sparring or Katas etc.) (ex. Aikido, Tai Chi, Kung Fu) and styles for competition into Combat Sports (ex. Boxing, Kyokushin, Kickboxing) and self defense systems like Krav Maga or other close combat styles from Military.
Thoughts about self-defense systems vs martial art:
By that I mean that there is no beauty in anything taught there, no style, no rules, no restrictions, just simple plain action and reaction, training to save your life or the life of your family or friends or any other 3rd party.
I say to 'train', because if the moment of reality comes, there is no guarantee that the things you have learned will be recalled - everybody reacts different under stress.
This leads me to the next point, a self-defense system should simulate real life scenarios, create stress weather through noise, multiple attackers, darkness ... surprises etc.to simulate an uncontrolled environment.
Every day aspects should be covered, driving in the underground, bus, swimming-pool, car even picking up money from ATM should be part of it, usage of common objects like coins, keys (even though pretty dangerous for the user if not properly held), sand, chairs, jackets, Pepper spray, knifes, Kalashnikov, pistols ... screw-drivers?
A self defense system has also the responsibility to provide information about safety, law about self-protection and provide information about the correct behavior for current possible threats (Terror attacks etc.).
Basically no boundaries whatsoever and that, in my eyes is no martial art.
I agree that martial arts evolve over time, we would not have Mixed Martial Arts or Daido Juku, even some of the 'modern' combat sports like Kyokushin-Karate would not exist, but that doesn´t change the fact that they still have rules,
time restrictions during fights, protection gear and referees.
A self defense system would miserably fail in following those approaches and would miss the reason why it exists, being close to reality.
Again it really depends what one wants to believe, my opinion on Krav-Maga specifically is based on being a Krav-Maga instructor for many years and talking to and learning from some of the main influencers of it.
Everyone is free to have his own opinion :-)