Up to around 7-9k lbs, a 1/2 ton can be a great option.
Where you see people start recommending 3/4 or 1 ton trucks is when you have people asking if they can pull a 10-15k lb trailer with a 1/2 ton. At the lower end of that range properly equipped the 1/2ton might be in spec but the jump up to 3/4 ton will pull nicer.