We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
Many people exercise these muscles for athleticism or for appearance. Part of exercising "the core," as they say. Is it worth doing? Well, it can't hurt especially as we get older, but almost all calisthenics and heavy weights challenge those core muscles pretty well. Planks are the only core-specific things I do and I do them because I am told to.
It is near-impossible for a woman to show a six-pack, and it seems like a silly pursuit for the average guy. For one thing, it takes a body fat of roughly below 9% to uncover the divisions of the rectus abdominis assembly.
What the ordinary exerciser can achieve with exercise and proper diet is to be "cut" vertically, ie having a clear demarcation between the rectus and the obliques. I think that ought to be a plenty good-enough conditioning indicator for man or woman. It is an indicator of somewhere around 15% body fat and of decent but not extreme fitness.
At 15%, you will still sizzle nicely in the crematorium but you will not start a conflagration. At 25% you are chubby and begin to be a fire hazard.
A pal of mine who works out bragged to me that he doesn't have a lousy six-pack - he has a whole keg.