Just ordered an Apple cable a couple months ago directly from Apple through their Apple Store app, and about $1K USD of Ring security gear off their web site for exactly this fraud reason. If I know I want to purchase a name brand object, I now shop at the manufacturer's site first; if I don't
need the Prime delivery aspects, and there is no significant difference in pricing, then the manufacturer site gets my consumer information.
And I haven't even been bitten by the Amazon commingling fraud yet, just bitten by egregiously craptastic products bought off of Amazon. I can't trust the reviews without carefully parsing them to figure out which ones are likely factory-generated. I can't trust the pricing without looking through various historical price add-ons. At that point, the cognitive load between using Amazon and choosing alternative channels is pretty meh, and I'd rather just go "straight to the source", ordering direct from the manufacturer and finding the manufacturer by looking up forum discussions.
For renewing household goods, I'm finding myself shopping at my local grocery chain, Target and WalMart a lot more these days. Once Amazon pricing for the same household item shows it is more than these other sources (and often by a surprisingly large delta), Amazon doesn't get a crack at that spend for another year, as it isn't worth the cognitive bandwidth to comparison shop each time I go to the grocery store, or if Target/WalMart deliver the best price, they get the subscription for the year. I use a credit card number generator for subscriptions, so we have to renew the configuration each year.
Amazon is losing its convenience value proposition, and I find taking their eye off of that ball very odd for a B2C context, but what do I know.