Gosh the box of dangerous generalisations must have been on special this week in your part of the world. While many non-technical managers "will have no idea what their people are doing" that doesn't have to be so.
In my 25 year career I've had the pleasure of having two non-technical managers who were far and away the best managers I've ever seen in action. They used their non-techiness to their advantage and built high performing teams that would walk over coals for them. It's called trust.... "I know you are all supremely clever, and know stuff that I don't.... that's why you're the engineers. My job is to trust you all to do your jobs well, make sure nothing gets in the way of you doing your job well, and by the way you lot being a bunch of arrogant techie dicks, and ignoring me as a "non-techie girl" counts as "getting in the way of you doing your jobs well" "
And to the point of the original article - Two of the absolutely worst managers I've had were promoted engineers who weren't good enough to make it into the ranks of "chief engineer / consulting architect / great poo bah of technicality" and felt their only scope for promotion was to take on management. To the credit of one of them, he realised he was totally crap at this management lark, and re-trained. Over time he actually became quite a good manager - not great but pretty good.
The other doofus left in a hail of "thank god he's gone" and continued to wreck havoc wherever he went.