What is particularly good about peer support?
Lab of growth hacks
Your peers, just like you are probably trying a bunch of different growth hacks, methods, and so on, to see what will work in their startup. Consider this as a lab of growth hacks - you and your peers together are simultaneously running tens of experiments at any moment. And if you communicate often enough, you can adopt the latest growth hacks and ideas that just worked for your peers. It is so much easier to learn something from a direct experience than from a book. This constant experimentation and exchange of knowledge create an efficient innovation machine.
Everyone who has launched a product and tried to grow it knows that there is no silver bullet for startups. Especially in the early stages, all you need is to have constant feedback on your efforts that fuel constant iterations. A mentor will soon become part of your startup and won’t be able to spot caveats as good as a network of peers would do. Imagine, you have 10 fellow founders in your peer network. That is 10 different unique perspectives on how to do business and potentially 10 different view-points on your startup. I’d argue that these 10 founders can give quite a bit more rich feedback than a mentor would do.
Often the advice you need is “just go and start doing it”. We like to slack off, don’t we? The best cure for that is to see how hard others work. When your friends say how he did 100 cold calls last week, while you did only 10, how will you feel? You will be motivated to catch up. This peer pressure is giving a good post to your current efforts.
Peers are people just like you, in the same situation as you. Some physiological aspects of humans make our tough moments less tough when you know you are not the only one suffering. In tough moments you can relate to your peers much more than to say, a mentor. Even though you may not be co-founders with your peers, you feel you are one big team in some sense.
Your source of co-founders
You never know when you will jump on a new venture (e.g. after the previous startup will fail, like 9 out of 10 does) and realize that you need a co-founder. Or maybe you need a co-founder already now!
Your peers will be obviously the primary source for potential co-founders - you hopefully know each other for some time and worked lightly together by meeting and helping one another with advice and feedback. You have built that trust and bond by helping each other. You know what they are good at - they probably gave you some advice and it worked out for you. And you also know what they are currently up to - are they considering starting a new venture, becoming a hands-on advisor, or joining a startup.