Outlook content archivation to a separate storage file is a specific knowledge area which has its own settings in Outlook application and its own recommended practices. I'd recommend making the meaning of the tag clear enough by adding annotation and performing some clean-up on tagged questions. From long-term viewpoint, I think it could be beneficial to have this as long as this is a distinctive area of the usage.
Regarding Raystafarian's comment:
You are right, archive is just another pst file. But typically, even average Outlook user sooner or later has to cope with archivation-specific things like:
In my case, is archiving a good practice or a must (due to limited Exchange online mailbox size)?
Which items to put in archives and which keep in main storage? How to effectively set up archivation options? Are there some scripts around for smarter (selective) archivation?
Is one archive enough or create new archive every year? (growing pst files lose speed)
Keep all archives attached to Outlook (ready-to-use) or only open them on demand?
How to effectively search in archives, even in disconnected ones?
This is why I wrote that from certain viewpoint, Outlook archivation can be considered as distinctive area of knowledge. But still I consider myself a relative newbie on the SE network, so I'm leaving final consideration and decision on you.
.pstbut it would be better if it included pst and ost, rather than adopting the pst tag, just make synonyms?