Street photography community wasn't small it was just segragated, prior to online communities the only way to see street shots were through books, magazines, exhibition and local prints.
With the explosion of sites like Flickr in the mid 2000s, it got easier to see and share street shots to the rest of the world but after 2010 with the popularity and availability of smarth phones, most people were checking pictures on their phones and unfortunately Flickr doesn't run nicely on smart phones.
Instagram works great on any phones and allows you to view your peers work and share your work all in one app, anywhere you are, plus it allows you to share your works which isn't necessarily taken with the phone.
I have a buddy that joined Instagram years after me and has earned thousands of followers compared to my 200s, how? he was marketing himself out, posting at least once a day and using as many hashtags as he could get, something that I don't really want to nor have any interest in.
I tend to use Instragram mostly as a journal/album.
But yes, I follow some RFF members, some street photographers including some Magnum photographers on Instagram as I find it inspirational and also nice to see others work.
Regarding camera phones, IMO they are actually great street cameras, really small, silent and inconspicuous (since everyone have camera phones now a days) and I'm not afraid to use it to take some shots, whether street or landscape since it will only be shared to the web and/or printed no bigger than 8x10.