A cord trailing from your back ankle creates some interference when you're cross-stepping toward the nose. It gets underfoot. It can pull tight as you move further from the tail. A coiled or kinked leash will genuinely disrupt your footwork.
But the solution isn't to surf without one. The solution is the right leash, set up correctly.
What actually causes the problem
Almost always one of three things: leash too short for the board, ankle attachment when knee would be better, or poor cord quality that kinks and tangles easily.
A 6ft leash on a 9ft board is too tight. The cord runs out of slack before you're halfway to the nose, and it pulls your back foot. This is a setup problem, not a fundamental leash problem. Match your leash length to your board and most of the tension issue disappears.
Ankle attachment keeps the cord in the direct path of your footwork. Moving to a calf or knee leash raises the attachment point and pulls the cord back out of your way. This single change makes more difference to cross-stepping comfort than most surfers expect.
What the no-leash camp gets right
Surfing without a leash does sharpen your board awareness. When there's no cord to retrieve your board, you become more intentional about your exits and less careless with your dismounts. Some very good surfers find real value in the discipline it creates.
But this applies in specific conditions — small surf, uncrowded break, real skill. A loose longboard in a busy lineup is a safety issue for everyone around you. It isn't a style statement.
The practical answer
If you're developing your cross-stepping, surf with a leash and focus on the setup: correct length for your board, calf or knee attachment, quality cord that doesn't kink. You'll lose almost nothing to the leash and keep the safety margin that matters.
A note on cord quality
A cheap leash with a stiff, poorly made cord will tangle and interfere far more than a well-made one. Construction matters. A leash that sits naturally — without coiling, without pulling — is one you stop noticing entirely. That's the standard worth aiming for.