“I paced around my parents’ house, talking nervously, trying to keep up with him [David Foster Wallace], vainly trying to impress him. He refused to give me the validation and satisfaction I wanted. It’s not going to come from writing, he told me. Writing can never do that.”
Maybe it had better, yes? If writing is going to be a large part of one’s life, and that of others, then as with any act it is certainly healthy if writing really does help provide a sense of self, as it does in good amounts for many people.
A Practical Policy 
But then clearly DFW wasn’t feeling particularly “healthy,” was he? His writing obviously mattered a great deal to a lot of people, but if it did not provide him with “validation and satisfaction.” I don’t really think we can insist that it should have.
I’m referring to the view in general, one I’ve heard before. I don’t “insist” for DFW or anyone else. I have no idea how DFW was feeling during the conversation. I say nothing about it. This is my general view and observations. Others will have to decide if it is of any consequence to them.
I take Roscoe’s ending with this anecdote to be an implicit suggestion that Wallace didn’t find “validation and satistfaction”–or at least enough validation and satisfaction–from his own writing and that this perhaps to some extent accounts for his last desperate act.
That’s possible but seems ambiguous and otherwise open-ended to me. Who could be in position to say? So I address my comment generally, as it seems to me DFW meant his comment, generally, at least in part. Again, it’s the sort of general statement and sentiment I’ve seen expressed before, whatever else it might have been. But back to the point: If DFW had added “only” and said, “It’s not going to come from writing only” – then I would have been in essential general agreement with him. There’s a lot more to life than writing (of many sorts), but writing can be a substantial and rewarding part of life.