Why don't hashtags apply for previous content?

Not sure how to word this, but I’ll try my best.

I have a series, Emotional Car Rides, that I started long before the hashtags feature was live. I applied the #emotionalcarrides hashtag to them all when I posted them at the time.

I recently posted another ECR and used the hashtag, but only that one comes up when I click on the hashtag.

I’d like to see Hashtags be retroactively applied. Anyone else feelin’ this?