yes it's doable, but actually our fees are also very easy to see - this is just 1% of the total deposited amount, can be checked at blockchain.info
Suppose you have collected 100 BTC in deposits, your fee is 1%, and your public address currently holds 1.1 BTC.
I can tell that so far you have collected 100 BTC.
So I can tell that you've "earned" 1 BTC in fees.
But I can't tell whether you've withdrawn your fees or not.
So maybe you already withdrew the 1 BTC, and the fund has 1.1 BTC to pay out future payments.
But maybe you didn't, so the fund only has 0.1 BTC to pay out future payments.
Or maybe you took out some but not all of the 1 BTC fee, so anywhere between 0.1 and 1.1 BTC is available for payouts.
This ambiguity makes it impossible for potential investors to make informed decisions.