Ah, another one of your strawman arguments, I see. No, a MacBook weighing just two pounds would most likely be more than adequate for the job, if an under one pound iPad wouldn't do it VPNed back to a full desktop computer, with BOTH displays and having complete control of it. However the view might be a bit tiny. . . so then you might want the iPad Pro with its 12.9 inch 2732 x 2048 pixel screen. Or, alternately, you can hook any of them up to a miniature video projector and display them on the wall at whatever size you need to show your clients. They are all capable of doing that. . . in either HD or even 4K.
However, most sales professionals are opting for the iPads.
You don't pay much attention to what people answer to you, do you? All of this has been asked and answered. . . and essentially covered in the article and other sources on the movement of Apple products into business, if you bothered to read them.
Again, fanbois deciding what is best for someone, but have no idea what they do. You are a sales guy, you tell the old lady that she needs a $1200 iMac to get onto Facebook. You have the entire catalog memorized and you rehearse the sales pitches perfectly, good for you. But unfortunately, it all you know...
Why do they need desktops? Why do they even need offices to house those bulky, outdated desktops?
Business is about efficiency, not buying every Apple computing product on the planet.
You are still thinking in the old 1950’s office with Apple Products instead of IBM Typewriters..