Emoji might actually be usefull for quick oversight, but how can you include a reference to an issue for every commit? What if you are just adding more tests?
It tends to act as resource management, you shouldn't be working on things that your manager doesn't know about at least enough to make an "issue" for it.
But it's not a 100% must in all cases, just that there SHOULD be a ref there. The rule of thumb for us was if it's going to take more than 15 minutes, it needs an issue.
Edit:
I can't seem to reply any more, but this is just for organization. you can create your own issue and work on it on your own, this is just a way to organize and categorize the commits and provide an easy "parsable" way to give some context to them.