Centralized exchange owners can call their whale buddies to push the price in either direction thus liquidating millions of dollars, perhaps hundreds of millions worth of leverage trades, in less than an hour.  Maybe in minutes.  In some cases the exchanges may have the fiat or crypto reserves to achieve this without outside help from said whales.  If the cost of the pump/dump is less than the amount of leverage about to be stolen it makes perfect sense.

It's free money.  Furthermore, proving this would probably be very difficult unless you were on the inside.

I hope the recent freezes on BTC withdraws pushes the -not your keys, not your coin narrative into peoples faces. Perhaps the recent talk of all time low BTC custody on centralized exchanges is true, and they all go out of business. Which could give rise to decentralized autonomous platforms.  Either free of leverage trading, or the code might be able to be written to mask where the leverage exists at any point in time.  Thus making the hypothesized calculation of pump/dump cost to leverage positions a stab in the dark, and risky for the manipulators.