Because 99% of the people saying that the "whales are manipulating the markets" has no basis at all and are just saying that so they have someone to blame for their bad trades.
Also, do we even have proof of a hedge fund shorting bitcoin with huge amounts of money?
It fully depends on what people understand as manipulation. For many coins (and especially alts) the majority of trading volume is coming from market makers who is using MM bots in order to keep the price in specified range and making buy and sell walls which normal traders are unable to break.
Also, the support and resistance is usually broken on very large trade volumes which also indicates that major price changes are happening due to whale orders.
And yes, some of the market makers are hunting stop losses. This is why it is better to set a larger SL if you trade altcoin futures. But generally, this is not a big problem.