GitHub streaks and the associated green block graph is often used as a bragging right in programming communities. The more dark green or the higher your streak, the "better" programmer you are. Having an active GitHub profile is often seen by recruiters and businesses as the sign of a strong developer.
For me, the green blocks and streaks became a way to motivate myself into working on code. Not for the benefit of others, but to continue my education and learn to add components in small, succinct chunks, rather than spending a whole day on one big commit.
There is a lot of literature emphasising the concept of smaller commits:
...so this was a useful change to my personal git work flow.
I made this change at the start of 2017, clearing my profile of previous commits and setting up new projects. With the addition of private repositories being included in the contribution chart, I was able to add work privately on personal projects, but still see the blocks on my public profile contribution chart.
GitHub recently removed the actual streak count, which would show how many days in a row a user had made commits. But for me it's not about the "days in a row" functionality, it's about visualising my education and the little green blocks are reward enough.
I can understand those who have concerns about the streaks:
But for me, this is gamifying work I want to be doing, rather than procrastinating.