I agree with Hicks sentiment that the crank "giving" is more likely due to worn parts or misalignment. The crank would have to flex a lot to actually be responsible for ghost shifting, which would make it incredibly poor quality. Sheldon's article strikes me as cursory for "When Should You Stand"...
Assuming you have the gearing for whatever you're riding (reasonable terrain), yes - there shouldn't be a need to stand to pedal. Bypassing what Sheldon covered about gearing and saddle height...
From a road riding perspective, standing takes less effort because you can use body weight rather than legs to crank over. It's used a lot when hill climbing - gives the legs a rest, and the opportunity to sprint when others don't know to. The gist I got recently was "if others are standing, so should you" - it struck me as prudent if you don't know the route, otherwise ride as you feel comfortable.
Standing is often used to initiate a sprint on more level ground, to get the momentum up. But depending on the speed, being out of the saddle can mean your body is creating more drag -- counteracting what you intended to do.
I stood while mountain biking on a hard tail (no rear suspension), for psuedo-suspension. I remember my quads getting a workout until I built up the strength. I still habitually take weight off my saddle when riding road.