Depends on what you mean by 'need a road bike'. An Enduro bike was designed & meant to be primarily ridden off road. If you ride off road most of the time, you already have the right bike. A road bike simply can't take the punishment of riding off road. It wasn't designed for it.
On the flip side, if you ride an Enduro bike solely on paved surfaces, you have the wrong type of bike. Hypothetically, two riders of equal strength, ability & skill going all out on a paved cycleway, the one on the road bike wins hands down every time. 1. The road bike has narrower, high pressure tires for less rolling resistance. 2. The road bike is more aerodynamic. 3. Bicycles are becoming more & more specialized every day. Choose a bike based on 'where & how' you'll be riding.