I also see more and more map notes which describe a change in the future. Sometimes more than 18 months in the future. Until the work has been finished, nothing can be changed on the map. Because of that, it is not possible to make a city “green”. (ie. resolve all map notes in an area).
Maybe limit the usage of notes and clearly describe what map notes should be used for?
For example:
No questions. (like is this a path?, does this shop still exist?).
No future changes, only notes which can be resolved immediately (after a survey).
Only important missing features. (a missing road or supermarket is probably ok, but missing street lamps certainly not).
However, I don’t mind anonymous notes. Sure there are some invalid notes, but I can close them easily.
I don’t see this as a problem. We’re not running out of database space. Perhaps it would be better to implement clientside filtering so that you can, for example, choose to only see notes posted within the last three months.
The handling of notes should be agreed on the by the local community. In Stuttgart there was some controversy about notes in the future. So every todo which is 2+ weeks in the future is now collected by me in https://wiki.openstreetmap.org/wiki/Stuttgart/Todo.