Exactly. Even if I don't have a camera with me, I always have a smartphone with me... I don't carry a tablet around all the time, but if for some reason I did, I'd still use a phone or camera to take photos as it's easier and better quality.
If you're at e.g. a wedding, a party, a night out, a day trip, a weekend break, or anywhere else where you may want to take planned or unplanned photos, a camera or phone is far more convenient to carry around all the time than a tablet and will also give better photos. Quality and convenience.