Why do you need watercooling fittings?

[lenni.michel]

Let´s say we build a custom watercooling loop with hardline tubing and we are experienced with bending it (no, I´m not). What do we need those fittings for? The pipes go in the other components (waterblock, radiator...) and since we don´t have 2 short tubes but one long one, technically, there are no fittings required, are they?
I know, I´m a beginner but with custom watercooling people explain all crazy kinds of things but mostly overlook the basics..

 

[Darkbreeze]

Fittings are required to secure and seal tubing to components, such as GPU card, CPU water block and radiators. If there are no breaks in the line between components then you don't need fittings between components, only AT the component where the tubing terminates.