During my trip to the Philippines, I was able to confirm the reason why tourists do not stop in the cities, but rather come to enjoy the country's natural riches, like empty beaches, or again to discover the most curious animals. The main reason is that these cities present little cultural interest and are very disorderly, with infernal road traffic in particular.
For me, even if it is in Indonesia, Padang Sidempuan has all these unfortunate characteristics. It is situated in the north of Sumatra Island and after a few hours spent going all over it, I found nothing of interest. There is one traffic jam after another all day long, making any attempt to enjoy the city difficult.
This is why I do not recommend that you make a stop in this city.