I occasionally add fitting but missing tags to posts, for example if the question is about a monster and is missing the tag, I add monsters, or if it is about the action economy, but has no such tag, I might add action-economy. I typically do this when not all five slots on the question have been taken yet, and there is "white space" to add something without needing to boot something else out that the author (or other community members) added.
Since I'm curious about portals, in the sense of "connections between times, places and worlds" I sometimes browse questions about portals if there is nothing else new or interesting going on. This is actually not that easy, because there are a lot of false positives:
Tales from the Yawning Portal is a collection of adventures for 5e, and often pops up
Adventures that involve the eponymous Yawning Portal, such as Waterdeep: Dragon Heist also come up
A website called "Obsidian Portal" also tends to feature in the results
These one can exclude by query language such as "-obsidian", which is a bit laborious, but feasible.
In 4th, there is a number of teleportation spells that function by means of creating a portal to step through. Sometimes the qeustions are about the actual portal, but a lot of the time, these are just questions about teleportation that the portal aspect is not important for.
There are of course also mundane portals, doorways, that show up
These latter cases are not so easy to exclude, because they do not share a common element.
Because of all of this, I find the portals tag especially useful, because it can help to find questions that are not primarily about teleportation, or any of these other things, but about the concept of a gateway to a different reality or place. And if I find a question that would benefit from it and has open space, or if I answer such a question, I tag it.
When I was new to the site, I used to tag a lot of questions in one day for another tag (glyph of warding, which was later decided to be replaced with spelltrap, because individual spells normally do not have their own tags) flooding the "front page" with questions related to that. I was told that was bad practice and one should not do it.
I'm not doing that here. This typically is pretty low volume, I might create one or two such tags in a week, and certainly less than one a week on average. Is this a problem?