One of the problems in the above suggestion is in the above. This might work on a LAN, but one should consider the case when the server is on the other side of the globe than the client. In that case the ping becomes much higher (at least 133ms since that is the time that light would need to travel the distance, so it probably will be 250-300ms, try https://www.meter.net/tools/world-ping-test/). This will give noticeable lag on moving the camera, opening any menu, highlighting units etc. Secondly, I doubt many players will have a computer able to compute the rendering for all players and observers. Sure one can come up with neutral servers who are able to compute it for small matches (and yes dedicated/headless servers are definitely something wanted), but having a reliable ecosystem for this is another (financial among other things) issue.

We already have a filter for maps that are "Best for MP". We also have a filter for "Naval Maps" only. Default is just the same as "All Maps", if I'm seeing right. If you install "Community Maps" mod, it adds a filter for them. Add in filters for "Random Naval Map" and "Random Land Map", and it won't be overwhelming. We can just mimic Age of Empires 2 for this, no need to make it complicated.

Taking your idea further: some "fair" third guy with an OP computer hosts 2 virtual machine instances each with a 0ad process running inside. Then each VM is made accessible 1 player via parsec or TeamViewer or whatever. Both will then have to play according to the rules that you have set up in your VM. And then the latency and network lags kick in...

I think there first needs to be some change as to how the categories for the dropdown are set up. Right now one map category has to be called "Default" in order for it to be the default, which is not good. after that the procedure should be to better organize existing maps like I tried to do, and then remove truly redundant maps like Kerala. My thoughts are if there are only 10 to 20 maps per category. Things will be less overwhelming.

Maps removed could be moved into a "all maps" mod, so they're still available if somebody really wants to play them.

"Bad" maps can be challenging and the imbalanced design can be viewed as additional fun factor, especially if the map is pretty or "looks cool". Pompeii, for example, is a horrible map. But, it looks cool and the buildable layout provides some challenge to the player. A better criteria would be to either remove or update maps where the AI is broken. No use in keeping a map that's useless for SP.

This topic is important, but please don't delete too many maps. I like the lack of wood for some cards, but it could be mentioned in the card description. The new migration map is nice, but it clearly strays from the purpose of the migration; it's more of an island map. I understand that we don't want to have multiple versions of the same map because we have to make choices. But I prefer quantity over quality. Let's keep quality for the scenarios. It is possible to have a second version with gaia unit for some scenario? If a card is not of interest, put it in a separate category.