I have noticed that there is a limit for number of posts that I can flag. The limit value seems to decrease without being restored. Why is there such a limit? We earn the ability to flag posts after gaining certain reputation, that means gaining some trust, why add the limit then?
Most parts of the system have rate limits - usually daily. Flags are particularly notable:
- somebody (moderators, admins, etc) will probably have to review that flag
- it could contribute towards getting a post deleted maliciously
for both of these, it is desirable to minimise inappropriate use, while still allowing a reasonable level of genuine use.
It's a daily limit and the number should be restored the next day - in UTC.
You get a minimum of 5 flags and then more are added as you get more rep.
Most simple answer that comes to mind: Trolls.
If people could have flagged as many posts as they wish, trolls could use this to flood the moderators with false reports and cause "real" reports to get no attention.
This alone is good enough to pose a limit.
If you are asking in the general sense of "why have limits for anything?", then read this: