thoughtfulFor example, if I were to give SFSFC $1000, I could then deduct that from my income for the purpose of determining how much income tax I owe. More importantly, if I attend a convention primarily for the purpose of representing SFSFC, or if it's an SFSFC-run convention on which I'm working, I can (generally; it's complicated) deduct from my taxable income the expenses I incurred such as meals and hotel rooms and travel, treating them as cash donations. (The value of my time is never deductible.)
(If you wonder why these travel costs would be considered cash donations, imagine a different money path, where I (say) give SFSFC $1000 (thus a cash donation) and then SFSFC reimburses my ordinary expenses incurred as their agent to the tune of $1000.)
As you might expect, I would be strongly opposed to removing the charitable tax deduction or to significantly narrowing the definition of what a "charity" is. I like the American system, and I think that saying "only donations to the poor are worthy," is a step down a slippery slope that leads to removing the deduction entirely and saying, "Only the government can choose what is really worth of public support." While the tax deduction (which I have sometimes taken) isn't my primary motivation for my volunteer work with fandom, I believe that removing the deduction would have a chilling impact on charitable giving of all sorts.