If you already have money, deflation is good for your net financial position, sure. If you work for your money, deflation could mean your boss has to either cut your wages, or fire you. Even if that money can buy more, people are very unwilling to take a pay cut.

That means if there’s a sudden (but small) drop in productivity in an industry, inflation can paper over it, and deflation amplifies it, and potentially means the industry collapses.