Invite

 Supposedly, some groups do not invite membership.

There is supposed to be some fascination/attraction on the part of people to ask to join.  This is tempered by a selection process, also supposedly strenuous.

It can be.

It can be otherwise.

Timing, placement and association fosters a certain amount of invitation.

Masons and MENSA are 2 examples.

They generally deny this, but it exists nevertheless.  

There are those who attest to this.  

For whatever reason, some are made to consider affiliation.  

It is up to the individual as to whether they accept.

Some refuse, wishing to be unbound.  They have their cake and eat it too.  Then they can gather for particular purposes and go to other actions later.

Some believe an official association gets things done better.

Let your conscience be your guide.

What do you need and does it serve a purpose individually and/or the whole?  What purpose?

Perhaps it's profit and loss.  

Weal or woe.