@FediTips Notes for new users: this can be useful, providing you don't mind your timeline being so busy you struggle to find the posts of accounts you follow.
The reasons for this are:
- There is no way to move followed hashtags to a list to declutter your timeline.
- It ignores your language settings, so you'll see matching posts in all languages.
Fine for niche topics. Nightmare for, say, your sportsball of choice. 
tl;dr: Following hashtags is useful, but it has its problems.