Because of the 1930s’ Great Depression, with money being as scarce as Habs goals, it was decided that having two teams in Montreal just wasn’t economically feasible. So the Montreal Maroons, winners of the Stanley Cup in 1926 and 1935, folded after the 1938 season, leaving the Canadiens to carry on.
The entire 1930s had been a struggle. In the early part of the decade, the Montreal Canadiens were doing so poorly both on the ice and at the box office that they were considering moving to Cleveland. (At least they could have kept the same crest.)
And to make matters worse, the Canadiens were even thinking about folding a couple of years after the Maroons had bit the dust, leaving Montreal with no NHL team at all.