For sure. I skipped a 0% loan because the additional cash off the car (one of those 0% or additional $x.xx off) made the loan a worse deal, when looking at the average performance of taking cash from investments. It's very dependent on the rates, yes. The bigger issue is people buying more car than they need. And then putting thousands in accessories on it. I mean, if it makes you feel good but imagine putting the 22" truck rims, lift kit, and low profile tires into that investment people are talking about earning 12% per year...Sure, "it might". The tone of your post wasn't that "it might" matter in some situations but that this was a widespread problem in America of short-term thinking, poor long-term planning, an aversion to delayed gratification, and an attack on conservative values.
My point is for LOTS of people it probably makes perfect sense to take a low-interest loan. It really isn't that difficult to qualify for the low-interest loans and most people with a 401K can kill 1.9% in performance. In the end, I agree, everyone's situation is different but many of these posts (not just yours but others too) present the idea of taking a loan as being bad or negative or a sign of poor judgment and it very well may not be the case.
But yeah, sounds like many on here actually calculate the difference given averages, which is good.