There is a lot to be said for cheaper tickets and fewer teams playing fewer games.
Also those NBA and NHL games are sellouts (or nearly so) and MLS games are played in 60,000 seat football stadiums.
The Sounders in Seattle sell out Century Link Field. Same place the Seahawks play. Seattle’s bonkers about soccer.
That was true 20 years ago, but today most MLS teams play in there own stadiums, built with less taxpayer dollars than the other sports.