that is definitely not feasible, vandals can also use JOSM
sadly, vandalism is not limited to deletions
some vandalism waves mass editing thousands of names to include slurs/insults/informations that were not name of given object etc
or deleting names from 400 000+ objects.
It could help to provide few minutes of screen recording of an example of affected session. At least minute-two of editing resulting in rate limit blocking edit (I use Peek on Linux for screen recording, there could be also other tools)
Not entirely sure what kind of edits gets blocked and whether it should be blocked.
Looking at edits from new accounts almost triggering rate limits would also help to judge situation.
Note comment
Where new users map their first changesets very quickly, and especially when they do so in JOSM, there is a clear correlation with poor-quality editing. A significant subset of DWG tickets created about new users have simply been about poor editing quality, and our advice is often “slow down, and make smaller but better quality edits”. This has been more noticeable since the recent waves of vandalism where large number of objects were edited (or deleted) in a short period of time - we (the DWG) have been using various means to detect this, and in a few cases have found ourselves dealing with poor quality new editors who just needed to be encouraged to slow down a bit.