It's a cost/benefit thing. If you can protect yourself from potentially losing thousands of dollars for next to no cost, why wouldn't you? As rates go up, next to no cost turns into an actually noticeable cost, and now the cost/benefit starts to not make much sense.If I am worried about a few thousands I shouldn't be purchasing a 60k plus car.
I do think it's a rule of thumb that gets overstated in many cases, especially in the days of higher interest rates, but it's a real risk that people should be aware of and understand how to mitigate.