Yes, it is!
But Zcash (ZEC) has a unique problem because more than 2 million ZEC were distributed during the Founder’s Reward era… that in my opinion tarnishes the otherwise fair ideal of “Pay-to-win” (because not everyone has paid for their ZEC)
(And of course there are also the current 4-year cycle of Dev Fund ZEC that have been freely distributed among the ZCG, ECC, and ZF)
Among those ~2 million ZEC distributed to the publicly unknown “Founders” we haven’t got any concrete way to know how many of them could press down the needle during coin weighted voting events. (This situation is a bit more cloudy than that of ZCG, ZF, or ECC using their ZEC for coin weighted voting… since afterall, we have some capacity to "know" the activities of their ZEC)
Taking this very first iteration, merely ~420k ZEC voted, out of a total circulation of 15 million!
Until Transparent ZEC are able to vote, I’d assert that there is a great risk of any coin weighted voting event being controlled by one or just a few of the original “Founder’s Reward” recipients.
Put concisely, we have all now seen that Zooko is friends with a ZEC whale who is in control of more than ~350K ZEC! Pay-to-win is the ideal, but how can we be sure that the whale actually paid?