When you turn the crankshaft and move the piston (using the kickstarter), you are moving air from the crankcase into the cylinder. So while cylinder pressures go up, crankcase pressure will go DOWN if the intake is sealed off. It's a closed system, you're just moving it from one place to another. The only way to pressurize a closed system is to add pressure from an outside source.
It's like going to the ATM. Pulling $100 out of your bank account and putting it in your wallet doesn't make you "richer", you don't have more money overall. You have the exact same amount of total money, it's just in your wallet instead of your bank account. The only way to get "richer" is to add more money from an outside source like a paycheck.
