That argument may have held some ground when the NBA and NHL still had two divisions per conference and thus you were guaranteed to have good teams as division winners, but with the split from 2 to 3 in '98 for the NHL and last year in the NBA, the situation has now arisen where you can have weak division winners getting the 3 seed ahead of teams with better records.
Notable examples of this would be the Southeast division in the NHL pretty much since it was formed in '98, and the Celtics winning the Atlantic in the NBA this year... yeah, they did wind up with a decent record, but remember for a good portion of the season everyone in that division had a losing record and it had become a joke in the sports media.
Before this year, even with three divisions, the only time MLB ever came close to having a sub-.500 team in the playoffs was the Rangers in '94, but that season was a black hole anyway so forget that