This is a blue sky thread, clearly.
Mods like CRMOD or CAx had sophisticated match joining logic that is far too high of a burden of expertise on the average modder.
The average modder should be concerned about game-flow, not administrative controls.
Any loose or vague ideas on how this could be done in the engine. Or whether it should be done. The engine supplies cvars like deathmatch 0/1/2/3 and teamplay and samelevel.
I'm not saying the engine would be the whole solution, as the above cvars live mostly or entirely in the QuakeC. At the same time, it seems like voting, match participation and even admin controls are rather uniform in how they work and topics that a very finite number (like can count on fingers on both hands not using them all?) really are experts with.
I guess I'm asking, in an ideal world how could these be implemented in a way that represents the lowest burden on a modder. You might make a freeze tag game or dodgeball or some fun mod, but the work required to make them "multiplayer dedicated professionally hosted public server ready" is rather steep. Issues like a new player connects, or an existing player disconnects that was in the match, controls for allowing a new connecting player in the game and so forth. (FFA is simple, whoever is present plays.)
[Hosting a multiplayer server is different than single player or LAN, obviously. Case in point, in stock id1, if you get the silver key and disconnect --- the key is gone forever! No connecting players can ever complete the current map. One example. Which is one reason I dislike closed-source Quake mods, they never think of stuff like that or other multiplayer problems. Mostly out of a lack of expertise in the area, but nevertheless the problems are real and absolutely terminal. Anyway, since that isn't the subject. I'm just trying to think of ways that more mods can become truly server friendly without imposing unfair burdens on a QuakeC guy]