I think I'll put my two cents in, whether or not it's useful or appreciated. While I haven't been here for quite a while, I also have had the experience of being here during what I guess was the middle-to-tail-end of the golden age you've been referring to. My stance on it is thus: While everyone should be expected to inform the games they're in (or at least the GMs involved) of their inactivity, people shouldn't be punished for it. A million things could happen to cause inactivity and plainly people should get the benefit of the doubt whether they deserve it or not.

I'd like to think I tenaciously hang on to RPGs that I join, and that I don't abandon any, but I may very well be overlooking something I don't remember. In my experience though, no small number of RPGs have died because the GM evaporated just when the game needed a push. The GM may have come back with a perfectly good reason for having been gone without notice, but the RP is still left dead. I don't really think anyone should be punished for that. It's not my call, but I don't think any rules should be made to enforce the longevity of games. While it is an issue, I think that as the quality of games (hopefully) goes up, it will right itself. Technically GMs now have the right to refuse anyone from joining their game, don't they? If that GM feels strongly about certain players that are known to ditch not joining, they can keep them out themselves.

*leaves her two cents on the table*