I don’t know if people that maintain such lists take that kind of thing into account or not

It takes more work to find out who is purchasing the books, particularly if the publisher includes straw-purchases as part of its marketing strategy and therefore has an incentive to report their number inaccurately.

I have no trouble believing that Lil Alex found some demon willing to help him game the Steam system.

He's got enough money to simply do it himself (or outsource the process to professionals). Sort of a priming-the-pump method to marketing. Its very possible that the vig Steam gets from your straw purchases is less than the cost of paying them upfront to advertise your game. Also possible he's doing both, in which case Steam has a strong economic incentive not to discourage this behavior.

At one time the NY Times bestseller list put this dagger (†) icon at the end of the summary when it happened. That way people in the know would get it was because of bulk sales.

But I think NYT changed how they do their best seller list to be a survey of booksellers, and probably just don't include bulk sales at all anymore. But I don't know. But if you see a dagger on a bestseller list, it means shenanigans are afoot. (†)