WAIT WHAT? It means me and my friend spent that Fu** days on a plugin that won't be sold... Can I know why it's not allowed?
Because everyone makes those kind of plugins with the goal of getting rich and not putting much effort in. I'm sure that if you designed a KitPvP plugin that was so top-notch and well-coded and feature-packed and went above and beyond what a normal KitPvP plugin would do, then I see no problem with it being available for purchase. You could also list the plugin as a free resource to build up ideas from the community, and then release a paid version with a larger feature set.
So, for example. We created a KitPvP plugin with all top notch features, such as tournaments, own permissions system and way more top notch stuff. Would we (Me and AdityaTD) be able to sell it ?
Kit plugins and KitPVP plugins are just completely banned, full stop. I'm not bothered to find md_5's twitter post, but there were basically just way too many no-effort plugins. Sure, make some sort of plugin that includes kits (e.g. kits for a minigame), but premium plugins for the sole purpose of selling kits are not allowed. That's not a good thing.