MLB is the only sport where this is a problem because MLB is the only sport that treasures it's past more than it's future. (Steroid use is prevalent, sometimes rampant, in the NFL and NBA and even the NHL and nobody has ever cared).
Dan Marino's 1984 season was unfathomable at the time. It'd still be a great season today but nothing eye-popping. Contemporary QBs can and do match and surpass his totals, and the best of the best are expected to. Baseball has a guy have that kind of year and they want to prevent it from ever happening again. Football has a guy have that kind of year and wants as many guys to replicate it as possible. Bart Starr is now a Who? Johnny Unitas is now a Who? [Don't make me say it about Joe Montana but you get the pattern]. Even Tom Brady, impossible as it may seem now, will someday become a Who? when the shield needs the new guy to be the best ever.
Baseball still insists it's best ever has been retired for 87 years and dead for 74 and anyone who does better must have cheated so it doesn't count.