Many brands won't sell on Amazon because they automatically side with buyer, even if they bought wrong part, installed it wrong, break it, then return the item, where seller has to pay for original item, two shipping fees and often a free replacement. This is fine for cheapo stuff that costs pennies to manufacture, hence the abundance of stock that fits that description, but actual good quality items can have significant costs if they're broken/damaged constantly by brainless customers.
Louis Rossman did some videos on this which were great. Basically a lot of technical stuff on Amazon these days is imitation rubbish with fake reviews. If you're sure you're getting a branded item where you trust the brand, it's fine, but even then there are often issues. For example, I bought a 7950X3D BNIB dispatched and sold by Amazon, box arrived empty. Replacement was fine, but the free game AMD was marketing at the time, code had already been used for that CPU. Lots of stuff like that.