1. He makes a good point 2. Its not the point he thinks he makes 3. Full disclosure one of my degrees is a B.S in finance but I work as an engineer.
He makes a point that "At the end of it all, most business-school graduates won’t become high-level managers anyway, just precarious cubicle drones in anonymous office blocks." But isn't that true of most degrees? I would argue even most STEM grads end up in the cubicle farm. I saw plenty there working for a defense contractor. I also think him saying this is objectively bad is a little elitist. Depending on background and family socio-economic status the cubicle farm might be a step up and even a point of pride.
All of his criticism is from the point of view that people in business schools take advantage of others, how about people go to business school to not be taken advantage of? To know how to negotiate a salary, to know the rough rules of the game. If you don't come from a family of means I would argue a decent business school and STEM are about equivalent in terms of increasing your income and providing a long term career. Some don't have the aptitude or inclination to do STEM. Just like many STEM grads couldn't sell someone a $100 bill for $95.
Another claim is that: "Another suggested that the likelihood of committing some form of corporate crime increased if the individual concerned had experience of graduate business education, or military service. (Both careers presumably involve absolving responsibility to an organisation.)" How about people who know a field and are in the field are more likely to commit a crime in it? I am sure the number of blue collar embezzlement is dominated by plumbers/electricians etc. Not even going into criminal medical issues such as corrupt doctors being opioid prescription factories.
I am not saying all business schools are useful, or that they do the job perfectly but his opinion seems shockingly naive. Also business school might not be a good place to be if you don't have some degree of faith in capitalism (the single greatest eradicator of poverty over the past 50 years), it would be like being a flat-earther in an astrophysics department.
Finally, I would much rather be managed or HR-ed by someone with at least some formal training on how to treat people with dignity in difficult complex situations. I have seen conflict/layoffs/firings etc. handled absolutely atrociously by (albeit young) STEM grads. Admittedly having a degree in Management/HR doesn't mean you are automatically good at this, but education helps.
Personal anecdote: My first year in finance taught me a lot about debt, I changed my whole college strategy to graduate debt free. My finance degree also taught me most of the wealth management industry is exploitative of the average investor and have no demonstrable gains over just buying low fee indices. These 2 bits will save me hundreds of thousands of dollars if not over a million dollars throughout my career. Sure they may be obvious but millions of students every year make egregious financial mistakes to get other degrees that may land them in the same cube farm.