You’re going for a workout, you get your gear on, walk/run/drive yourself on over there and at some point during your workout you decide that you want to do some core work.
So, what do you do? You find an empty space of floor, or a decline bench and start doing some sit-ups or crunches, maybe you…
This is why I don’t bother with “ab workouts” e.g. 200 sit ups, 200 bicycles, 200 bridges, or whatever the latest cool thing around tumblr is. The lifts mentioned are more effective and infinitely more functional than pelvic thrusting off the floor.

