I think you and the parent comment are talking about different scales. A large SaaS company deal could be $300k per month per customer, and the sales process for a company like that can involve changing the software to meet the needs of the customer. A very early lesson is that what the customer says they need is not always the same as what they actually need.

One of the many reasons calls happen is that customers say "I need XYZ feature in order to do this deal," and the salesperson then needs to ask why they need XYZ feature, and what they want to accomplish, and maybe existing ABC feature actually meets their need, or maybe the company needs to develop XYZ feature to secure the contract. Once you get into a complex domain, that is not happening over email.

The article contains good advice to many businesses out there, but it's worth considering the situations where it doesn't apply, too.