Well, this specific reply bot listens for users that send replies to your posts and will reply to you in telegram. Why would you want this? Well, it's for correspondence. If you want to engage your readers/viewers through replies with telegram on a post, you can do that with this bot. It basically proxies all replies to your telegram conversation. Any responses in your telegram conversation are automatically sent to steemit.
You could just use esteem or busy for pretty much the exact same thing, but telegram gives you the ability to correspond like you would with a text messaging app with emojis and even the use of telegram apps.
Now bots in general on steemit are for different reasons:
- Convenience bots can be used to automate normal tasks that you would rather not do like claiming rewards or upvoting your favorite blogger.
- Augmentation bots can be used to add features to steemit that aren't there for you now. You can do this by augmenting the existing api or just creating automation.
- Data mining bots can be used to gather data from the blockchain that you don't normally see through a blogging app like steemit. Some of these things are like how much money you are making, what your reader conversions are like, etc... This is probably the largest use case of bots because there are so many that literally scour the blockchain for things like spammers, plagiarizers, suckers, etc...
You may also like running a digest bot. Something that creates a newsletter type thing based on some data you collect and pushes out in a known format each week. A friend of mine was thinking of writing an arbitrage report bot that would post arbitrage reports for people that follow that sort of thing.