Sometimes, Ideas are posted by users that have solutions or workarounds that meet the user's need. When others in the Community respond with these suggestions, the ideas usually end up in a status of "Not Planned".
I think it would be really helpful to be able to mark these as "solved". An example of this is the following post:
https://community.alteryx.com/t5/Alteryx-Product-Ideas/Copy-and-Paste-Data-Directly-Into-Canvas/idc-...
Here, the user posted a suggestion, and I as well as @mcarrico were able to provide suggestions that met this need. I think marking this post as Solved could help other users who have the same thought in the future.
I also think that this might be an opportunity for an additional tag for Community ideas, either "workaround available" or "already implemented". "Not Planned" doesn't necessarily read as well as it could in cases where a solution exists.