I would argue that the season and the postseason aren't trying to do the same thing, so you can't judge them the same.
The goal of winning the regular season is to score more points in the same amount of games as everyone else. A balanced schedule is an integral part of the equation. Team B with fewer points can claim that they would have scored more with Team A's schedule.
The goal of winning the postseason is to be the last team standing - put another way, to have everyone else lose before you do. An unbalanced "schedule" is fundamental element of the competition. In a playoff, no other team can claim they deserved it over the winner due to a "tougher path," because by losing, they are demonstrating their undeservedness to hold the Cup. Here, if Team B tries to claim they would have won the Cup if they had Team A's path, Team A can claim that Team B had the opportunity to be Team A's path, had they not lost.
But that's just what I'd argue, if I was the kind of person who likes to debate.
