I don't have any immediate need for either tag, but something looks like it needs to be cleaned up there.
filter has "DO NOT USE THIS TAG" because in this site it's considered a meta-tag. From Let's clean up some meta tags:
- filter - Can't possibly work as the only tag on a question. I see it used for gmail (it should be gmail-filters), google-spreadsheets, yahooemail (which should be yahoo-mail), youtube comments. This also seems to run afoul of the second point above (it means different things to different people).
The above link also invites the community to participate on the meta-tag clean up and includes advice about how to do it.
Related
filtersis a synonym forfilter, it would be very helpful if it had a description saying exactly that. ¶ But the real question is, what is the point of having a tag whose description begins by shouting at me that I shouldn't use it?