I have written about this before and am starting to wonder if I am actually in the wrong…

If you are hosting a Twitter chat and want people to use your hashtag everytime they engage (the whole purpose really) then why make your hashtag so long if you only get 140 characters?

I have seen some hashtags that are like 20 characters long and whilst I appreciate you need to use your hashtag to identify the topic, should you not be abbreviating just a little and keeping only one of two key words to identify? 

Can anyone tell me why people do it? Am I missing something key?