the opinion-based tag was introduced quite some time ago with the removal of the rule that completely prohibited opinion-based questions. Since then maintaining the tag was quite an issue. Many opinion-based questions weren't marked with the tag, and some questions that were nearly 100% based on facts were for some reason tagged as opinion-based.
Reviewing the questions under opinion-based tag today shows questions of all kind and as such, I feel this tag has lost all its meaning.
Opinion-based questions themselves will remain on the site and people can still ask them. What changes is that they won't be using the opinion-based tag anymore.
There are also a few types of completely opinion-based questions that are essentially just discussion topics and not questions. Those will remain prohibited as they belong to discussion forums more. They are all listed here: meta.tibiaqa.com/1135/questions-completely-opinion-therefore-suitable-tibiaqa
If you have any concerns, feel free to let us know!