We need meetings for the same reason we need online forums like this. We can meet other people who are comfortable with us and with whom we can feel comfortable. For many of us, there have been many shared experiences (of discrimination or not) that enable us to support and encourage each other in an often hostile world.
For example, in selecting a table for dinner, we have had assistance from others here and onboard that enabled us to find friendly waiters and staff who would help us to have a wonderful, memorable cruise. That contrasts with experiences we've had years before in which we were obligated to sit at dinner with tight-lipped homophobes who could barely manage to be courteous, let alone carry on a warm sympathetic social engagement!