It's a good advice not to drive. I drove heere for the first time during my 2nd time to DR, I was with my ex, and we made it Santo Domingo to Monte Plata, from there to Punta Cana (and from those days I had a conviction there was a road between Bayaguana and Hato Mayor, which after many and many drives turned into a convicton that I made quite a detour that day ===this is off topic===), drove back PUJ-SDQ-PUJ (in one day) and then back from PUJ to Santo Domingo. Santo Domingo is a mess for first time drivers and it took me time to get confident driving there. You need to know major traffic arteries and how they are relatively positioned to each other, in order to make your way around and find your location if you get lost (it's always easier to drive you if you know some reference points and how to get to/from those reference points).
If you drive, you WILL be tired upon reaching Santo Domingo, if you are not used to the traffic and rules of the road. If you travel any day with the exception of Sunday morning, roads will be full, and becaus eyou do not know the "spots" where it's safe to pass, etc., you may be stuck in the slow-moving traffic. Also, you need to be a good driver (European driving style) to be able to analyze and undertake risks passing cars, many times in narrow roads, with 30 vehicles in front of you. If you are only used to US highways-style driving (put the music on, the "D", and off you go) it would take you something like 4 hours or more to get from Punta Cana to Santo Domingo.
All in all, I do not recommend your driving to Santo Domingo during the first time visit. If you want, rent a car and visit the "countryside", such as Higuey, Seybo, Miches, Macao, etc. to get a gasp of local driving culture. Next time, Santo Domingo, maybe.