3 wood off the tee is oftentimes not a bad idea. I wouldn’t say you should always hit it instead of your driver (except in situations where you just cannot find control and accuracy with your driver). Most of the time 3 wood off the tee is appropriate when driver is just too much club. For example, let’s say you hit your 3 wood 240 yards and you hit your driver 265+. You may come across a hole where at around the 250 yard distance from the tee (as just an example), there is trouble (like a creek, lake, bunkers or any kind of hazard). In this situation, it’s a good idea to hit your 3 wood off the tee to lay up and not find the hazard off the tee.
Strategic course management is huge and can really go far.* 3 wood off the tee is also a good idea when you may have a narrow fairway tee shot to find more control (in a sacrifice of distance).