Issue: XF Newsfeed pollution with many edits of same articles by same person.

I think the only improvement that can be made to this is when the news feed entry is first created -- not to add a new entry if there is a previous entry about the same wiki page + same type of action + by the same member + within a certain cutoff (maybe 1 hour since last edit), rather to update a counter in that case and update the entry time. However, this would not protect you against a flood of many users editing many articles. The only way I can see preventing that would be to add an option to remove edits from the news feed altogether (something I don't think you want to do).

Is it not possible to replace newsfeed entries with updated entries?

i.e. Replace:
User1 has edited the page BlaBla

with

User1 and User2 have edited the page BlaBla

I also think that the solution you propose is a good one:

This change is implemented in 4.1.x.

A new admin setting:
Minimum Time since a User's Last Similar Activity Entry
If a user performs new activity similar to their previous activity that occurred within this many minutes, the previous activity will be merged to the new activity, rather than generating separate activity entries.
Default: 1440 minutes (1 day)

Obviously if the minimum time is too high, this will continuously bump/roll the same entry into the future. So 1 day is probably the longest you would want to do this. Due to a limitation in the database, after 2000 entries are rolled together, a new entry will be started, even if the minimum time since the last rolled entry has not been reached.

When activity is merged in this way, there will be an entry like:
This only applies to certain types of activity:
- Comments (per discussion)
- Edits (per page)
- File Updates (per page) -- this did not generate forum activity before 4.1.x
- Feed Entries (per feed) -- this did not generate forum activity before 4.1.x
- New Chapters (per book) -- this still only generates wiki activity