"Consulting" is a term so generic and ill-defined it almost doesn't mean anything at all.
When I did software consulting, I was basically a decent "modern" web dev brought into crusty old companies to bring some new perspective and approach. I'd help with some project direction and initial implementation and try to get a team up to speed to continue the work. I typically embedded as part of the team for a while and did plenty of hands-on design, coding, and troubleshooting work right alongside.
But this was just a small consulting shop, not one of the big "strategic" consultancies. Very different worlds.
The first sentence of the article explains that this is about management and strategic consulting.
This is so wrong it hurts. You'd be amazed at how often "I will save you $X, guaranteed, or your money back" is a non-starter when selling to companies.
I've spent a career very slowly gaining respect for enterprise sales people - going from "Ugh, sales people are all snakeoil salesmen" to "I can't believe what they do is even possible, much less regularly done" over about 20 years.
Selling software to large organizations involves finding a champion within the org, then figuring out the power structure within the org via an impressive sort of kremlinology. You have to figure out who loves your product in the org, who hates it, who can make the buying decision, whose approval is needed, who's handling the details of the contract, and so on. You need to understand the constellation of people across engineering, procurement, legal, leadership, and finance – and then understand the incentive structures for each.
Then you have to actually operate this whole complex political machine to get them to buy something. Even if it's self-evidently in the interest of the whole organization to do so, it's not an easy thing to do.
Anyway, all that to say: "b2b sales are easy" is... naive... to say the least.