Most people base their opinions on a company's prior products, yes.
The best way to learn about what your experience will be like three years from now is to look at what people who have owned that company's products for three years are experiencing now.
If Dell (or you) wish to argue that their current products will be vastly better/more reliable, etc. after three years of ownership, they are free to do so, but the burden is high, since it's purely speculative, and contrary to the real-world experience of people who put their hard-earned cash down.
If the company didn't build a great product with an excellent reputation before, they've got a lot of work to do to convince me they're now making something amazing.
Apple has many faults, but a three year old MBP is still an excellent machine with substantial retained value, and a high expectation that it will give good service for many years to some.
A 2013 Dell... not so much.
Have you ever asked yourself why nobody in their right mind buys a two-year-old high-spec Dell laptop at less than half the price of a new one to use for school?
Why aren't YOU looking at a year-old or two-year-old high-spec Dell? They're cheap as hell pre-owned. Probably under $500 for a machine that sold 18 months ago for $1500+. Absolutely KILLER price/performance. You can for sure get Broadwell, and even an early Skylake if you're willing to go up to $600. You'll get 90% of the specs of the current model for 1/3 the cost.
But you don't want one, because you KNOW that it's probably not worth it, even at 30% of what someone paid for it last year.
Because this is the first dell with somewhat decent build without being bulky.