Concerning exchanges closing registrations,that's normal because the exchange platform can't handle infinite members because hosting limited performance etc..They had to close the registrations to expand their capacity of members by upgrading their servers.Thus,it's not really a manipulation from exchanges.However,whales are kind of manipulating the market we've seen this many times now a whale sold his coins and a huge wave of sells followed him.
Most exchanges are whales themselves and I won't be surprised they may have an inside trader who would be doing the manipulations. Things like this should be spotted and not allowed to happen in any market as it affects the free and fair movement of the market based on real demand and supply.
It is obvious that fake signals are being created to mislead traders and investors, bots keep doing their thing based on how they have been programmed for manipulation, and so on.
Due to lack of mass adoption, bitcoin market is still under manipulation. Only when bitcoin marketcap to be hiting multiple trillion dollar levels, we may assume those manipulators will come to a point where they will not have power to move the market direction on their own wishes.