It's important to think about the counterargument, I agree.
To counter your counterargument: it's not a good argument on many levels (scope, allocation, distribution mechanism, effect). The main reason is that this sort of charity doesn't improve the core problem of low(er) social mobility. The opportunity to pursue self-development/self-fulfillment should not be tied to the whimsical act of a better-off person but presented to everyone as equal as possible - through common goods and services. The impossible future is impossible due to vastly different prerequisites. The person's "greatness" will never be seen, as most likely they will never be presented with the opportunity to display it.
That's a really nice thought and I agree, but it doesn't answer any of the practical questions the current of many countries often poses. Imo a, maybe temporary, solution that protects these artifacts is necessary.
Sadly FP will not change for these kinds of reasons, which is not saying we shouldn't push for it nevertheless. In the meantime I fear not much good will come from an idealistic stance but rather practical solutions that at least preserve the hope we can at some point in time marvel at artifacts in their proper context. Just my opinion though