I unfortunately must disagree with you here. For one of my services, a reddit post and a youtube video were all I needed to get 200 users overnight.

Now, most of them didn't pay, but I can assure you they were beating down my door for more service and more features and etc.

That's nice, but:

1) 200 customers, even if everyone paid, is an order of magnitude less than I need to pay my team (we're primarily a research&development company)

2) Our product/service isn't something you buy without a second thought on an e-shop, based on YouTube video or a Reddit post, it's a big, long-term and important investment that will be a powerful factor in the decisions of your company for the next 10 years and the selling process involves a great deal of analysis and customization, and of course internal negotiation and decision making at the customer's side

3) Our product/service isn't something you'd think you need before we offered it to you, and each company has very different needs

4) Everyone we're competing against has powerful sales teams, if we don't do it, everyone will buy from them because they got there first and the cost of switching is way too big