It’s fairly reasonable for a forum user to wish to prevent another user from replying to their threads. The current ignore feature is insufficient because ignored users are still able to reply to posts you create and continue to harm to the quality of discussion.
I propose another option to fully Block users. Blocked users will be unable to post in any threads you create.
There are two main concessions I can think of. blocked users will likely still be able to reply to replies made by the user who blocked them just because of the nature of a public forum, so it should be made abundantly clear to users that their blocks would only apply on the threads they make. Also, blocks would not apply in Bug Reports or Feature Requests related categories to prevent duplicate-posts.