Question: Why did the ancient sages seek isolation to do tapas?

Babaji:

Some did and some didn’t.  It depends a lot on the individual temperament. In the present day, one needs to encourage and inspire the student - the teacher cannot simply force them. No need to say or teach that you need to go to the forest and so on. The Guru will have to see the temperament of the student. It is simply a choice of a way of life. One can do tapas even in the house. Some sages in ancient times remained in the town, or even married. Sage Vyasa was married, though his son Shuka Maharishi stayed a bachelor. There are no hard and fast rules, it depends on what God wants.