An article I'd mentioned before by Dan Kelly, an in-depth history of martial arts ads in comic books, explains why.
After a judge ruled that Joe Weider (yes, that Joe Weider) had made false claims in his advertisements for, among other things, martial arts instruction books, many instructors (or printers of books) scaled back dramatically on their ads.
This is one of the post-judgment ads, from a company called Universal. Of this ad, Dan Kelly says (much better than I possibly could):
Those ads that persisted had an anonymity to them. The Universal people didn't have a front man, but they tried the strutting peacock method of salesmanship. Perhaps taking a cue from Danté, Universal highlighted that martial arts weren't just for ex-military men with ramrod straight hair but were also for Starsky and Hutch iconoclasts who didn't really need Asian hokum to defend themselves yet wanted an edge to make themselves all the manlier. Clip art returned, but the hats, suits and ties of the old ads were replaced with funky, dry-look dudes in gis or turtlenecks, with big sideburns and even bigger mustaches. Post-Danté, martial artists got hairier, making the Tegners, Flemings and Reumanns look even more like Coach Crewcut.
A Universal ad opens with: YOUR HANDS AND FEET WILL HAVE SUPER FANTASTIC POWER!! Your hands will have the power of an axe and you can use your elbows, knees and feet as death-dealing clubs!...The open hand can deliver a single Karate blow many times more powerful than a boxing champions punch! You'll quickly learn all the vital striking areas that will flatten the biggest and toughest assaulter...FAST!! You'll reduce any assailant to cringing helplessness, in just seconds. You'll fear no man...ever! Our TOTAL SELF-DEFENSE SYSTEM is the most DEADLY form of defense and attack ever devised.More subdued than Weider's ads, Universal's ads removed all suggestion that the reader was bullied. Wretched clip art dabbled in cheesier metaphor, one poufy-haired karate mensch holding a fistful of dynamite. As a matter of historical curiosity, one Universal ad includes a martial art never mentioned before: Tae Kwon Do. This is the only instance I've come across in which a Korean style (versus a Japanese or Chinese style) is mentioned, hinting at the future market dominance of Korean schools.
I like the design of this ad because it reminds me of really crappy illustrations that accompanied old video game ads (which were about a decade away from prominence still). The mediocre rendering of the Karate warrior could have easily been used for an ad for Karateka.
This specific ad for Universal's Total Self-Defense System ran in Amazing Spider-Man #125, October 1973.