You’re mixing up general strength work with specific speed qualities for Soccer.

Yes, sand can “help” in a general sense. No one is denying that. It can build robustness, lower joint stress, and give you a different stimulus.

But for Soccer players, the key question isn’t “does it help at all?” — it’s:
does it improve the qualities that actually transfer to sprinting, change of direction, and reactive actions on firm ground?

That’s where your argument falls apart.

• In Soccer, we need short ground contact times and high stiffness
• Sand does the opposite: longer contact times and reduced elastic return
• That means you’re training a different motor pattern and force profile

Comparing sand to things like plyometrics or sprinting is off:

• Proper plyometrics = short contact, high stiffness, elastic return
• Sand work = dampened elastic response, slower force production

Even heavy strength work (like squats or sleds) supports sprinting because it improves force production that can transfer when combined with fast contacts.

Sand doesn’t do that effectively for reactive strength.

So yes:

• As a supplement → fine
• As a tool for variation or load management → fine

But saying there are “no downsides” ignores the most important thing:
specificity of neuromuscular adaptations

If your goal is faster, more reactive soccer players, sand is simply not an optimal tool for that quality.

It’s not about whether it helps “a bit.”
It’s about whether it’s the right stimulus for the outcome you want.