Ahh, what a disappointment. Being able to subscribe to hashtags is the feature I wanted to see for so long and when I saw the first comment, I thought they did it finally. But no, it's not what I needed. It should not be called "subscribing hashtags", but "pinning" them
That's what it is tho. You create a time-line filter that shows only posts containing those hashtags - is that not a subscription?
There are also more literal implementations for this like SocialHome [1] where you can click + on hashtags you like and public post with them appear in your home timeline
