You see the weirdest things at the gym. I have no idea what those two were planning on accomplish with that workout but it isn't going to develop a great set of abdominals, that's for sure.
When it really comes down to it, everyone has abs. The problem is that most people's body fat is too high so the abdominal muscles aren't visible. As a male, your abdominals will be visible once you are about 10% body fat or less. As a female, your abdominals will be visible once you are about 20% body fat or less.
The goal of abdominal training isn't to make the muscles larger because you don't want a big bulky midsection but rather to tighten and tone the midsection. I recommend doing at least 10 reps for each sets of abs with most working sets in the 20-30 rep range. The best ab exercises are things like decline bench lying leg raises, decline bench crunches, high pulley kneeling abdominal crunches, plank and ab rollers.