In theory, it is supposed to be a way to get your book or story in front of more people. When people comment on a tweet, it tells the algorithm that it is a popular post and shows it to more people.

If you participate in a writer's lift, you are encouraged to follow all the other writer's on the thread and they are encouraged to follow you back, which gets you more followers. You are also encouraged to check out the books in the thread and hopefully buy or download and retweet the ones that look interesting to you.

When they are done correctly, they can be a really great way to get connected with other writers and spread awareness for your books, but once they became popular, as with any good thing on the internet, they became inundated with spammers who didn't embrace the ethos of the idea. These people will drop the links to their books on multiple lifts without following back or looking at books that interested them. This makes them less enjoyable to participate in.

Does that help?