I think "it's always been that way" is a bit too harsh -- I think it's less about people huddled in a back room making a preconceived intention to be sexist and

I think "it's always been that way" is a bit too harsh -- I think it's less about people huddled in a back room making a preconceived intention to be sexist and more often through things like "Well, I'll start by calling my friends". Top that off with a bit of an echo chamber effect, "I'll get people for my panel who I've seen on a panel" and it's pretty easy to accidentally end up with a panel of men. But the lack of overt intention in the cause doesn't mean it is something to ignore, or that it can't be fixed. But being aware of "My life circumstances have led me to a situation such that if I don't pay attention when putting this panel together, there's a pretty good chance I'm going to end up with a bunch of dudes on stage." is important.