Well, Linus is not wrong on most of his points, I'd say.
Half of the biggest argument to not buy from miners (if you can sniff them out) is out of "moral obligation" to many. If you don't care, it's a moot point for them and then comes the second half, which is the technical aspect of buying used: wear & tear plus warranty.
Buying used is not inherently bad or nefarious. It's just that this time around there's more baggage with it. Much like with everything else you can buy used, it's a gamble and general params are mostly the same. It's always a gamble if the source is not reliable enough or there's no warranty/protection to be had with the purchase.
Wear and tear is a thing. Miners or "regular" users treating their cards like garbage is also a thing. Selling in bad faith is also a thing. Buying new doesn't protect you from a defective product, but at least it comes with a warranty and you're, to a decent degree, protected from that.
As it always is the case: it'll be up to your personal risk aversion and how critical to what you want this purchase is.
I personally recommend buying used, but with a lot of caveats. I'd imagine most knowledgeable people here would agree with giving a long list of warning and tips, otherwise, for most people with no time to waste, buying new is worth the extra cost.
Regards.