Maybe the video linked below will help answer your question. There are advantages and disadvantages to just about every element of hull design. In general, flat bottom hulls have good primary stability but sacrifice secondary stability, and the extent to which the hull can be heeled or edged before secondary stability is completely lost has a very abrupt transition. Flat bottom boats also tend to track less well and have a greater wetted surface area which increases skin drag.
Shallow arch hulls tend to be more user-friendly in rough or moving water if there are any significant waves, especially during those times you get sideways to the current or encounter strong diagonal waves. They also tend to deal with converging currents more predictably.
Flat bottom boats tend to resist heeling or edging which is an important element of control in river paddling. Also since the sides of a canoe are relatively vertical and the bottom of a flat bottom hull is pretty much horizontal, there is a more abrupt transition where the bottom meets the sides, i.e, a “sharper chine”. If you do heel a flat bottom boat you will tend to sink more of that chine into the water than you will for a shallow arch boat. And in the shallows if you hit a rock sideways in current it is very easy to “trip” over that chine. A hull with a more rounded contour will tend to ride over rocks and other underwater obstacles in a more predictable fashion.
For these reasons most river paddlers of yesterday preferred shallow arch hull designs to flat bottom designs and many still do. Whitewater canoes and kayaks with a more rounded hull contour are said to have “displacement hulls”.
Having said that, in recent decades many whitewater canoes and kayaks have gravitated to more flat-bottom, hard-chine designs. These boats are said to have “planing hulls”. Many whitewater play boaters want boats that flat spin more easily. And the sharper chines can be used to advantage to provide directional stability for ferries, make eddy turns snappier, or allow for “knee steering” or directional control of the boat by deliberately dipping one or the other chine into the water by weighting one knee or the other. But those boats require the paddler to be ever mindful of that sharp chine and develop the ability to shift weight immediately if the chine tends to trip over an obstruction or a strong eddy line.