Yes Thiel writes how sales is important.

He gives out a mental model to think how much sales is important for your company, and how much you should invest in it. On a scale from tiktok (viral) to Palantir, you have to increase your sales spendings.

He talks how advertising was important for PayPal (by giving some money(sales spending) for referring).

And he talks why small/medium sized businesses don't use softwares for day-to-day tasks. Because they lie (in his words) a dead zone of sales, the 1000$ per product.