I think you might be missing the perspective. A heavy deadlift is one of the most "focusing" exercises I know. You can't lift 500lbs+ barbell without complete, singular focus. That's part of the value I derive from this exercise.

Also, squats are harder to learn, require good shoulder mobility (which a lot of desk jockeys don't have), and, at a minimum, require a squat rack, which you're unlikely to have at home. Better yet, I'd advise to use a power rack, which will catch the barbell if you fuck up your balance and fall forward.

TL;DR: while I agree that squat is a better overall exercise, and one that the author of the article should be doing if they don't have the time to do anything else, it requires a lot more gear and training than a deadlift. It is, therefore, not very practical to do barbell squats at home. And if the choice is between a deadlift and no lifting at all, it's deadlift all the way. It hits the posterior chain and core pretty well, and all you need is a barbell and a set of cheap-ass plates.

One way to not overdo it out of the gate is to not use straps on the barbell - you'll be limited by grip strength which is pretty slow to build. You also get to build a truly crushing handshake that way, for when we're back to handshakes. :-)