Why some applicants don't join HBS?

11% Accepted Applicants Don’t Join HBS – Where Do They Go?

MIT Sloan loses nearly 40% of its accepted applicants. Chicago Booth, too, loses nearly 40%. Tuck and Ross, almost 50%.

And these are some of the best MBA programs around.
Where do these accepted applicants go?

Most to higher-ranked and rival schools such as HBS, Stanford, Wharton, Columbia, and Kellogg. And a small fraction drops out i.e. doesn’t join any school (for reasons to be covered later in this post).

It’s understandable that a Sloan admit is very likely to prefer HBS over Sloan, but why does an HBS-admit, sometimes, not join HBS despite its unmatched brand equity.