Simplest answer - fixed income, aka salary, irrespective of the movies made by the company.

Think about it - an independent girl has to actually ger her ass off the bed pretty much every day if she needs the money. Then there are the drawbacks of gonzo porn - deepthroat fucking, brutal DP's, creampies, hard ass fucking, black dick - the brutalities are endless

And now think of a contract company - they take time over productions with the aesthetic makeovers, u don't hafta get out of bed everyday cause ur gonna get paid no matter what, nobody is gonna ram their dick down your throat or make you take black dicks etc. etc.

Get it?