I think it reasonable to think that games with close parallel in the real world from before forums popularity (Multiplayer RPG, Mafia,FEF and so on) came from their original moved to forums.
Absolutely, for example Mafia was conceived in a classroom(so legend goes). But we can still web root connections within the forum game pantheon.
More of an issue may be how old games take on elements of newer ones. This convergent evolution is often why archaic gameforms stay relavent, but could be called something else today, but haven't.
Here is a venn diagram, which demonstrates some overlap:
Everyone is John is an unusual crossbreed between suggestion and competitive multiplayer.
That's an interesting way to look at it. But I feel a fundamental element of any suggestion game is popular vote. The take turn nature on a mechanical level is more traditional RPG, with a shared character gimmick.
Soft rules (GM makes up everything) vs Hard rules (RTD, well-defined rules explained at the beginning)
This is an important distinction, hard and soft. I will call them roleplaying and RPG. I see RPG as an extension of RP rather than a different branch.
Godgames likely evolved from civ-management games, which themselves kind of derive themselves from games meant to boil warfare down to a (semi-)simplified version, such as chess or Risk.
The proposed "massive scale" grouping is noteworthy, but may not be so fundamental after all. While there are some games that are always on this scale, and some that never are, there are also those that may transition from single character focus to large scale rule.
Many games of either scale could be reinturrprited in the other. Without fundamental changes for game mechanics, thus it is more a "theme".
I will be shifting this type of inquiry
here, for the reasons explained there-in.
You are free to discuss historical connections here.