They may also have data that >90% of customers who make a purchase choose/click in <10 seconds, and never scroll. Or may even take a different path entirely or similar.
They could interpret all of that as you inspected the product(s) on the page, didn't choose/click one, and _now_ is the best time to prompt you with suggestions to maintain engagement in >75% of instances.
You could also be one of the lucky few customers in a sacrificial control group unknowingly testing their new shitty popup to measure its impact on sales.
Whilst I can't say for certain that any of this is your case, I absolutely guarantee there are many retail sites that do this - I've worked at several now - and this is bread-and-butter material to data teams working with customer engagement.
Then the problem is people, and "they're just clicking close out of reflex!".
Cue hiding this, and results you wanted appear! Success! Raise! Promotion! Or, maybe more funding, due to signs of greater engagement.
I will say, generally, when I'm to the point that I'm entering credit card info, I've put up with it, but I have been chased off of sites by this use case before. Especially if that popup also crosses with some other popup and now I'm chasing down the tiny little 6pt light-grey-on-white little "x"s to click away the popups in the right order.
Actually, let me add that to my touchstone list. OF COURSE hiding the dismissal icon for the popup increases "engagement" with the popup. You don't even need to run a test for that, because what other result could it have? "We shrank the close icon, moved it to the lower right corner where nobody expects it, and made sure to kill the constrast even harder, and customers dismissed it 2.5 seconds more quickly on average"? Of course that's not possible. But... that's the wrong question! And AB testing is really good at answering the question you're asking, it has no mechanism in and of itself to see whether you're asking the right question. If you're getting down to this you've overoptimized.