that's a giant sign you need to slow down/outright stop your tech tree advancement and focus on building up your economy.
As for guilds not longer taking on new players because of SC costs in GBG's...
My own guild is more than happy to take a season or two of less farming and/or even dropping to Platinum League for a season if it means we can help young cities grow and become strong cities.
It's only 3fps/5 diamonds difference between Plat vs. Dia leagues, and the odd time we do drop down, we end up being more than strong enough to dominate the map and require less SC's anyways since we can always hold the center of the map effectively and keep plenty of provinces open for encounters.
Sometimes it's well worth it to pass on a few extra personal rewards, when the overall team rewards will be a greater gain.