Anyone that has revenue has salespeople. Twitter’s (and every tech company’s) sales staff convince large companies to spend money paying for Twitter ads. A good salesperson will be mostly paid on commission for bringing huge clients who spend millions of dollars per year on advertising. Their comp is high specifically because they can sell many multiples of that comp.
A salesperson that has the ability to call the head of an advertising agency and get them to answer the phone is maybe the most valuable possible employee in any ad-supported business.
I'm being pedantic just for clarification but not everyone that has revenue has salespeople. Correct me if I'm wrong, but you're implying a lot of companies you might think wouldn't have salespeople do in fact have them.
A salesperson that has the ability to call the head of an advertising agency and get them to answer the phone is maybe the most valuable possible employee in any ad-supported business.