firesnakearies
Explorer
Yes, actually.
Hmm. This is a good answer. I don't particularly like it, but it's sensible, well-explained, and it works.
I suppose this is the only option, if you want to allow people to make their own characters and drop in/drop out at-will, and you want to have one continuous adventure story for the "season".
The other options would be...
To have only a specific set of pre-generated characters, so that even if the various players come and go from week to week, the characters in the adventure remain the same.
Or, to have each session be a separate "episode" with little to no real narrative link between them.
But if you don't like either of those ideas, if that's not what you're going for, then I guess that your "it's always been this way" idea is about the only way to explain it. It's a good idea. I think I'd go with one of the above alternatives, personally, but that's just a personal style preference. Your way would certainly be viable and fun, and easy too.