Running with a group makes it impossible not to learn from each other. There is a collective wisdom of the group, which is a great benefit of running with a group.
When the little voice in your head tries to convince you to skip today’s run, your running group will hold you accountable. One of the biggest gifts running partners give you, is accountability. When there are others counting on you, it’s even harder to not show up to your group run. Most people stop running or working out in general because of a lack of accountability.
There is no better motivation than running with a group, because there is always someone who is faster, ran more races than you did, or is fitter than you are. Group runs are also a great way to bound with the other runners or walkers.
You only become a better runner if you practice and keep training. For people who have issues with motivating themselves a running group will help a lot. Having a regular (weekly, or daily) meet up with your running group will give you consistency and make sure that you will stick to your training.
Running with a group even benefits you on a mental level. Running in a group helps you put in more effort than you usually would. Just when you may want to quit, someone will encourage you to keep going, no matter if you are fast or slow.