Short sellers are often vilified by the mainstream media, CEO's of publicly traded companies & many institutional money managers which are forced, by prospectus or other security selection parameters, to maintain only long-side exposure to the market. I won't go into all the benefits that short sellers provide, such as liquidity and sniffing out corporate malfeasance while the masses are content to turn a blind eye as long as a stock is in a bull trend, other than to mention that short sellers, at least when short interest is at normal or above average levels, often serve as a backstop in a stock or the broad market during selloffs as short sellers are the only guaranteed buyers in the market.
When the crap hits the fan & things get ugly, long-side traders & investors can simply stand aside and watch while every short seller must close their position at some point, i.e.- 'buy' the stock (buy-to-cover). Long-side traders don't have to buy-the-dip, shorts, on the other hand, sooner or later must close out their positions & often do on the dips. This is why stocks with very high short interest often continue to rise (as existing shorts are gradually squeezed out) & when they do fall, the corrections are often limited as those shorts step in to cover their positions. Likewise, stocks with very low short interest don't have that large portion of guaranteed buyers & are often prone to very swift & deeper corrections once it has become clear that a new downtrend is underway.