"Bestsellers are more likely to be reviewed by major outlets. . . ." On the other hand, reviews in major outlets are not the result of bestseller status, since the reviewers see ARCs--advance reader copies--in order for reviews to appear near the release date. And the timely availability of ARCs is up to the publisher, not the reviewer, which means that it is the publisher who decides, ahead of any critical reception, whether a book is going to get the push necessary to be a quick success. Similarly, it is the publisher who sets the promotion budget that determines the kind and degree of visibility the book will have on and immediately after release. No budget=no book tour, no full-page ads, no author interviews (other than whatever writers can gin up on their own).
And for a book that misses the major-review window (in Publishers Weekly, Library Journal, NYT, and a very few others) because ARCs didn't go out at all or at the right time, all that's left is the populist/consumer channel: Goodreads, Amazon, and other word-of-mouth. Those might drive a book sufficiently for it to sell through, but only a cockeyed optimist would depend on that.
Which is not to say that reader support is useless--only that the machineries of success are driven by the publisher. Advice to writers: get a ferocious agent who will push the publisher to back your book--and be prepared to hustle thereafter.