I suspect the American left focused on LGBTQ+ issues because it was a "safe" mission.

Increasing official tolerance there was no threat to their donors or the wealthy in general. Nobody had to pay more in taxes or submit to meaningful government regulstion to enforce "don't explicitly fire/assault/refuse to marry someone for being gay/trans". Arguably those policies could have ecen come out of broader expectations for "stay out of people's personal lives" rather than making special cutouts and declaring a marginal group.

Looks impressive, accomplishes very little. Pretty much sums up the Democratic party for the last 50 years.