I feel you fam. On some humble brag ishh but I'm blessed to be a Timbers fan. We sell out our games every year even though we haven't won ANYTHING in the MLS. Teams do need the support of their local fans. Even though the quality ain't there quite yet how do you expect a league to grow without supporting it? It's a lot harder for the big metropolitan teams to gain interest in their club due to the fact they are competing with major NFL, NBA or MLB teams.
The quality of play is one factor too. There isn't really a club in the likes of (old)Man U, Real Madrid, Barca, Bayern or PSG who dominates their league year in and out in the MLS. There's parody which in a competitive stand point is good but without a dynasty, drama or a team everyone likes to hate it's hard to sell tickets.
Look at LeBron or Brady for example. Everyone loves to hate em but they sell tickets. We all tune in when they play against our team to see if we can go for that upset. I think what the MLS needs is that dude that is so good everyone loves to hate.
The interest is growing, but until we have a super star, homegrown athlete that is world class, or a villain it's hard to root for a league that is 3rd or 4th fiddle in every city.