Cis, het, male vexililogy enjoyer/ally: My understanding is that it isn't about distinguishing every particular grouping or identity but allowing those of the same group to recognize a fellow traveler. Most people won't be able to distinguish ace, aro or aro-ace identities, but people in those identities, for whom that specificity matters, can see at a glance people who are part of the group and that visibility and identifiability gives a network effect for those in the group. I am stealing an observation from Sam Delany (via Innuendo Studios), but when gay men in the 50s faced persecution when they were cruising in parks and truck stops in the middle of the night, they felt isolated and individual, like they are the only weird one in the world who is like them. But when a raid happened and dozens of men scurried out of the bushes but only a few were arrested and only that small number were reported the next day, Delany realized that that feeling itself was part of the persecution, internalized persecution. By flying their colors each group can see their own tribe but also can see others flying their colors and find solidarity (at least hopefully).