Your original idea is brilliant in theory and paper ONLY.
*It would turn into hefkeirus and politics awfully quick. Look at Israel, the Ashkenazim don’t believe Sefardi schools should be supported, the majority of Israelis finds no use in yeshivish schools, and the yeshivish aren’t makir the needs of the Chassidim.
*What happens when the brilliant fundraisers give the moneys raised by the community for the community to one whopper donor’s investment firm to help raise extra revenue. This is ma’aseh bechol yom in Federation funding. This exposes our tzeddakah dollars to extreme risk.
*There will have to be EXTREME oversight, auditing and open accountability to the community it won’t happen.