Yes, I've seen this idea everywhere. xD This would be extremely helpful as I hate seeing marshmallows everywhere.
I proposed an idea of this a while ago when the preset sync came out. I'm sure a similar process could be set up for markings and even items that players want to submit. The only problem I could see is the configuration files being updated with the markings. Maybe there can be weekly marking updates where someone organizes the file needed and submits it to the shared folder for the others. I'm not sure. But it would definitely be helpful to get rid of the marshmallows.
The other thing we could try is a mass marking list that everyone copy and pastes into the cfg file manually. Heck, that might even resolve the problem i mentioned above.
Though I am certain that not everyone will take advantage of this, it would be pretty nice to have. I doubt the game is going to be updated by kov. Maybe someone can arrange a mod that adds all that stuff in the game, though it would have to be updated regularly by that person and having a shared folder like the presets would be much easier.
Also a bit of a side note. If all the markings were to be added into the game, feralheart would need a new character creator layout. I can tell you there will way be over 100 markings if that compilation were to happen and it will be quite difficult selecting them with only the scroll navigation we have now to help us. (A mini search bar would be nice for each marking section.)