Exactly, its not something i would do myself, i maintain my cars to a very high standard and have never had a vehicle I own fail an MOT. It was simply an example of an item that isnt covered by the test even though it could potentially be dangerous.
You know as well as i do that the MOT is nothing more than a basic test of roadworthyness. It doesnt mean the vehicle is actually safe, and doesnt mean that it complies with all relevant construction and use regulations. However many people seem to use passing an MOT as proof that their dodgy modifications (such as retrofitted HID's) are completely fine, when infact it might just be that the tester didnt notice or couldnt be ***** looking properly, noticed it but thaught they'd let the guy off because its a modified car or couldnt actually fail it due to there being no option for it on the computer.
I do agree that since most people will take their car to a garage once a year, for an MOT and a service, if a part is showing signs of wear, but isnt quite hanging off yet, then it IS a good idea to fail the component even though it might have lasted another three months, because its entirely likely that a lot of drivers simply wouldnt notice that its become knackered 4 months down the line, and will simply ignore it.
When i had my first A4, i fitted some cheap control arms from ebay, unaware of their extremely poor quality and short lifespan. Approx 3 months after fitting them i had the car in for an MOT, and the guy gave me an advisory for the front control arms, saying there was a bit of play in a couple of the balljoints, but they'd probably last another year. This puzzled me as i knew they were only 3 months old, and i figured the guy was maybe just touting for work, hoping that i'd get him to replace them. Not much more than a month later, those control arms were clunking creaking and groaning, and upon inspection were literally hanging off. I ended up having to replace the lot with quality parts.
Had i been your typical Mrs Mavis, who was a bit tight on cash, its quite likely they'd have simply ignored the clunking and continued driving the car thinking "its only just passed an MOT, so it must be something minor".