The human species is full of folly, but no. Rowers didn't try to invent a way to navigate lakes, failed, and ended up in those paper-thin useless boats. Rowing is a sport, like judo, and Shoshin Shotokan karate is a self-improvement practice with the goals I mentioned, only touching on sport and street-fighting.

Practitioners do claim that their style is effective in real fighting, though they recognize that styles without the layer of traditional Japanese discipline, like Krav Maga, have their own advantages (and disadvantages).

But avoiding a street fight is the best way to win it. The inspirational stories told among Shoshin Shotokan karate practitioners about the lineage of masters, people like Gichin Funakoshi and Hirokazu Kanazawa, tell not how they bloodied a roomful of thugs, but how they scared thugs off with self-confidence, or at most, restrained them with a testicle squeeze.

As far as I know, karate originated as unarmed fighting techniques used because possession of weapons like swords by ordinary people was very much illegal. So the beginning was quite practical.

However Shotokan is a bit of a special case because its founder was of the opinion that competitions and contests were the wrong approach and the point of karate was, basically, self-improvement. I don't know whether the founder tried and failed (at effective combat) or just didn't try.

In the West there is considerable social pressure to restyle martial arts as a non-aggressive system of exercises which aim to teach discipline (in particular, obedience to authority), provide some strength and aerobic training, and make you look cool.