A tripod is only necessary if you are shooting at less the 1/60, If you tried you could move enough to blurr 1/125 or 1/250 shutter speeds. Faster then that it is hard to do.
Not entirely true for hand held photography.
Most amateurs will need to shoot at least 1/125 sec with a 50mm to provide adequate 8x10 print & larger than that you will need faster speed, but preferably a tripod. While advance photographers & pro could get a way with 1/60 sec & maybe 1/30 sec at 50mm if they really have to do it.
I can get adequate 1/15 sec photograph with a 20mm & good image AT 1/60 sec with a 50mm. But, no way in hell that I could produce good handheld image at 1/500 sec with a 500mm telephoto lens, and any one that claim that they can is a liar. (Canon have some ISM lenses to assist with stabilization that might produce 2 shutter speed slower than standard)
Handheld & focal speed standard - shutter speed guide
20mm ? at least 1/15 sec but prefer 1/30 sec or greater.
50mm ? at least 1/60 sec but prefer 1/125 sec or greater.
100mm ? at least 1/125 sec but prefer 1/250 sec or greater.
200mm ? at least 1/250 sec but prefer 1/375 sec or greater.
400mm ? at least 1/500 sec but prefer 1/750 sec or greater.
And, so on?.
The actual prefer shutter speed is about 2X the focal length for handheld, there for any thing that is beyond 200mm rapidly needs a heavy-duty tripod. And, at 400mm or greater wind shake become trouble some, therefore shelter for the camera & lens maybe needed to shoot below 1/250 sec.