I suspect this sort of thing gets promulgated because it kind of massages our ego, like yes, they can measure other sorts of productivity, but not ours, oh no, we're too complex and intelligent, there's no way to measure the deep sorts of work that we do! Which, yes, OK, we're not exactly bricklayers, but surely, if you had to, you could do better.
Measuring developer productivity should, in my opinion, have one dimension for speed, one for quality, and one for user impact. LOC can be fine as a measurement for speed, you just don’t want to look at it in isolation. You would want to also measure, for example, escape rate and usage for the features the developer worked on, and be willing to change or refine these if circumstances require it.
You also need to look for different profiles based on the developer’s level of seniority. A senior dev probably shouldn’t be writing as much code as a contributor, but their user impact should be high, and escape rate low. Analyzing differences between teams is important, as well. A team that has a lot of escapes or little user impact probably has issues that need management attention, and may not have anything at all to do with individual developer productivity or ability.
In brief, the numbers are there to help you make better management decisions, not to relieve you of having to make them.
Linux users can be defensive or even toxic about their operating system so I hardly blame the author for being impatient or frustrated. Still, I don’t blame people for being frustrated in turn at that tone.