An efficient, fast freestyle is a full body, connected and coordinated movement which involves the kick working with the upper body to maximize a swimmer’s ability to generate propulsion.
It would be the equivalent in running of saying we want to make you a more efficient runner, but you need to run with your arms at your sides and your arms shouldn’t move.
The best distance swim programs in the US 20-25% of the total training volume is kicking. There’s a reason for it.
If you have any other questions, please let me know.
Tim