On Openbook we try to use hashtags sort of like legos. They can fit together, and take on greater meanings, when combined.
A good example of this is the #intro tag, which you can read about there. Another one is #bugreport.
When used wisely, in different combinations, hashtags become a language all their own, allowing us to efficiently organize information, as well as organize ourselves into powerful movements.
This is similar to how you might use labels in your emails. You might tag something according to which part of your life it relates to, such as #work or #school, then also tag it according to how stressful it is with #important or #fun. That way you can search for "#work #fun" when you're looking for a certain email where your coworker invited you to a barbeque, and you don't have to look at all the impending doom and deadlines that you might see if you searched for "#work #important".
This is the antithesis of how instagram uses hashtags, because it only let's you search for one hashtag at a time. This causes every hashtag to become an enclosed echo chamber, or filter bubble, or psychological feedback loop, whatever you want to call it. Which means that every hashtag takes on a narrow meaning all it's own, and is shut off from any outside influence. It's very much aligned with the general walled garden principle that instagram is known for. For instance, instagram doesn't even allow external links, except for just one in your "bio", and it basically does everything it can to funnel people into a wormhole they can't escape from. It's very similar to how casinos never have windows or clocks so you can't tell how long you've been there, and then give out free drinks to keep you there longer.