Like others have said, Freemasons are one of several mutual backscratching societies - there is the RC equivalent, the Catenians aka the Murphia (big in Preston) - old school ties - the Buffaloes etc.
It's a characteristic of humans - we like to be in groups.
However I agree with Smilingcrow that these groups can be a pain in the veritable when you come across their capacity for opaqueness. A surprising number (or unsurprising, depends on viewpoint) of male headteachers are Freemasons - ditto high-ranking local government officers.
Having been given a rough time in a small-town job once, because a certain lodge member took against me personally, I can absolutely sympathise with the direction Smilingcrow is coming from.
But as for virtual Freemasons on AB......I'm wondering what the digital handshake looks like..... :)