Citadels are meant to be a group activity for clans, and RuneScape is a MMORPG afterall.
The Citadel resources needed for weekly upkeep have been reduced by 80% as of 11 December 2017 thanks to Mod Shauny. Since then, I can meet upkeep in my clan's T7 Citadel by myself without any other members helping with resources. We just need 4 other members to visit to reach the 5 visitor requirement.
The statements and suggestions you've made are a bit extreme. You don't need to have a Citadel for your clan, though it is nice to have. If you try to recruit, you may have some luck in finding members who are looking to build up a clan. If you can't get 5 members to maintain your Citadel, then maybe Citadels aren't for your clan. Focus on other areas and work on the Citadel later. Also, a clan of less than 5 members is hardly a clan, but they all have the ability to recruit. (assuming the permission in clan settings is enabled)
In the meantime, the Citadel's current upkeep requirements are fair for all clans. Considering Clans cap at a maximum of 500 members and you need to have a minimum of 5 to maintain a Citadel, any further reductions than the ones given 3 months ago would be way too much. Personally, I'd prefer to see Citadels removed entirely and replaced with something else than have further updates to reduce upkeep costs.~ Sicariu