Money allows a lot of worth to be removed from the system without any positive input and a huge amount to be removed solely on the basis of improved liquidity.
Suppose I have chickens I sell at £5, outside forces reduce the value of that £5 such that chickens are now worth £10. If previously a haircut was £5, and is since I cashed up now £10 (inflated the same as the chicken did) then because I use money I've lost 50% of the value of my chicken; simply by using money. If I swapped that chicken for a future haircut then it wouldn't matter what inflation does or the charges banks put on transactions or how competitors try to low-ball the hairdresser out of existence. I get a haircut, they get a chicken.
You can not escape the speculation, though. Either you speculate on money losing value, or on gaining value (or staying the same in value). In your example, if you sell the chicken for 5$ and through outside forces haircuts become so cheap that they only cost 1$, using money is better for you.
Also, the equivalent to outside forces devaluating the money would simply be the hairdresser dieing or moving away - then he got your chicken for free, because you can not call in your future haircut anymore. At least with money, you can still go to another hairdresser.
Suppose I have chickens I sell at £5, outside forces reduce the value of that £5 such that chickens are now worth £10. If previously a haircut was £5, and is since I cashed up now £10 (inflated the same as the chicken did) then because I use money I've lost 50% of the value of my chicken; simply by using money. If I swapped that chicken for a future haircut then it wouldn't matter what inflation does or the charges banks put on transactions or how competitors try to low-ball the hairdresser out of existence. I get a haircut, they get a chicken.