Bad preferences happen when Founders are overoptimistic or focused on optics (like a postmoney of $1.00B). Even the standard 1x/nonparticipating reflects a mismatch in optimism. Few founders would accept the valuations that would come with an all-common investment, so it's rarely discussed.
Yes employees suffer along with the founders when bad preferences are chosen. But that's still the founders fault, not the investor.
You're arguing against something I didn't make a point of. I never said it was the investor's fault that the founder signs a bad term sheet. Investors will generally pursue the best terms they can get, founders should do the same.
My obvious point is that founders and employees should conspire whenever possible - acting in their shared interest - to eliminate investor-favorable liquidity preferences as a common part of start-up term sheets.
Yes employees suffer along with the founders when bad preferences are chosen. But that's still the founders fault, not the investor.