One tag in particular is "Orphaned-blocks." There is no tag for this. It would be nice to be able to search on that tag. The concept is central to proof-of-work and scaling and network limitations. I think it'll come up in the future as the discussion expands into different PoW's or other potential protocol changes.
So, now that the issue is framed, is it okay to create a tag for a topic that may only get used once or twice, as long as the topic/tag is deemed important?