Do you agree that ripple is making a mockery of decentralization because ripple is involved in banks which are centralized. Ripple is rank number 2 base on market capitalization of cryptocurrencies.
What makes you think that it is mandatory for every single cryptocurrency that exists to be decentralized?
Sure it may make a mockery of decentralization itself because it is involved with banks, but that doesn't make it less of a valid cryptocurrency than Bitcoin.
Ripple solves a very widespread problem and is thus a great currency even if it's not decentralized.