Don't just block certain recipes, actually remove vanilla recipes from your server with RecipeRemover!
Either I'm blind or I'm surprised a proper plugin for this doesn't exist. This is useful to use in conjunction with plugins like CustomItemRecipes when you want to override vanilla recipes.
For right now, only a simple config option exists:
This list should contain the list of Material recipe results you wish to remove from the server. A list of valid Material enums can be found here: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/Material.html
Please do note that removing some recipes that are related to advancements may cause errors and warnings when worlds are loaded/players join. I'm not sure how it affects advancements (other than obviously removing the possibility of obtaining the advancement for the involved recipe), but everything else is working fine, and the plugins/worlds load despite the errors, so yea, just keep that in mind.
RecipeRemover must either be loaded on server start or when no players exist on the server, else it will refuse to attempt removal of recipes (doing so will corrupt the session of any logged in player, resulting in the server being unable to save anything they've done for that session.)