Github added similar emoji "Reactions to Pull Requests, Issues, and Comments" a few years ago:
This feature was specifically created in response to an issue raised in the "Dear GitHub" open letter sent by members of the GitHub / Open Source community:
- Issues often accumulate content-less “+1” comments which serve only to spam the maintainers and any others subscribed to the issue. These +1s serve a valuable function in letting maintainers know how widespread an issue is, but their drawbacks are too great. We’d like issues to gain a first-class voting system, and for content-less comments like “+1” or “👍” or “me too” to trigger a warning and instructions on how to use the voting mechanism.
In my experience these emoji have been hugely beneficial in GitHub PRs, issues, and comment threads - essentially a quick way to upvote/downvote a post, but also allowing you to express reactions such as "love" or "confused" or "celebration".
There's less of an obvious immediate need on SE, where posts can already be upvoted/downvoted (or easily edited/deleted) to solve many of the same problems raised in the GitHub letter.
P.S. here was GitHub's response to the community open letter:
Dear Open Source Maintainers,
We hear you and we're sorry. We've been slow to respond to your letter and slow to respond to your frustrations.
We're working hard to fix this. Over the next few weeks we'll begin releasing a number of improvements to Issues, many of which will address the specific concerns raised in the letter. But we're not going to stop there. We'll continue to focus on Issues moving forward by adding new features, responding to feedback, and iterating on the core experience. We've also got a few surprises in store.
Issues haven't gotten much attention from GitHub these past few years and that was a mistake, but we've never stopped thinking about or caring about you and your communities. However, we know we haven't communicated that. So in addition to improving Issues, we're also going to kick off a few initiatives that will help give you more insight into what's on our radar. We want to make sharing feedback with GitHub less of a black box experience and we want to hear your ideas and concerns regularly.
We'll be in touch next week. Sorry it's taken so long, and thank you for everything.