For as long as the American League East division has existed in MLB, it’s been universally recognized as the strongest division overall in baseball. Whether that meant the Yankees were dominating everybody else, or the Red Sox vs. Yankees rivalry was at its zenith, the AL East has never been ignored or written off.
Traditionally, if the Yankees weren’t steamrolling everybody, the Red Sox and the Yankees fought for first place while the Orioles, Rays, and Blue Jays half-heartedly aimed for third place (or, in the Orioles case, were just absolutely terrible). There were, of course, exceptions to this, but until the 2020s this was mostly how it was.