As Porto+Benfica have shown this season, teams can go unbeaten all season and not win the league, while a team who loses a game wins the league over them. The better accomplishment is winning the league while losing a game, compared to finishing second and not losing.
A team could go unbeaten all season and get relegated on 38 points after 38 draws, while a team could finish a place above them on 39 points and stay up after 8 wins, 15 draws and 15 defeats. The better accomplishment would staying up on 39 points over not losing and getting relegated.
Not-losing is a negative thing to look at in sport.
For me, the least impressive thing 2003-04 Arsenal did was go unbeaten in the league. I’m more impressed that they scored the most goals, had the best goal difference, won the most games and got the most points that season to win the title. Not-losing is just a thing on the side which wouldn’t even be considered when separating the teams if the team who finished 2nd had the same points as Arsenal that season.