If hydrogen is electrolytic you can as well make it on site. Steel mills are continuous operations and there is not much need to pool/smooth demand.

Shifting electric prices due to wind power is a strong motivation to pool it though.

So far it's easier and more efficient to reserve/contract some hydro (dam) storage than store/pool hydrogen for continuous operations.

That sounds very location dependant and not necessarily feasible at all given higher and higher share of wind power being used. That hydro will be needed during periods of low wind to stabilise everything else.

The whole point of the grid is to de-localize power.

Direct hydrogen reduction plants pretty much don't exist yet, might as well build them where electricity can be stored efficiently. Some of the biggest hydro plants were built specifically to power aluminium smelting nearby.