In a large stream boats allow you to effectively cover ALL holding water in the stream. Fish in large streams inherently hold in locations that are difficult to make good presentations from the bank, even if you can cast there. Ever watch a bank fisherman with nearly same gear as you hook fish from the other side that you already cast to?? (I have) Even on smaller to medium sized streams there some less agressive fish that will bite when you get closer and make better presentations. If you can stop your boat (or use a motor) to hold it in place you can litereally stop nearly anywhere (depending on the vessel) and make effective presentations. If there are only bank anglers just by virtue of where you can stand and wade to, MANY fish will never be fished at. The goal here is to reduce hook-ups (LOL) but still let a lotta people fish!