With excess wind/solar, pumped hydro would be the storage mechanism, but that clearly doesn't apply when a country has an excess of hydro too!
Many factories, office buildings, and even stores spend the majority of the day/week empty or very close to it.
Below that you have schools which often close for several months a year.
Entertainment venues even multi billion dollar sports stadiums may spend a lot of time empty. Where possible they aim for year round operations, but often it’s not viable.
Below that you have peaking gas electric power plants, as many grids pay for reserve capacity that’s very rarely used. Some extreme cases might not even be used beyond validating it still works in a given year.
A synthetic fuel refinery can operate 24/7, so would be budgeted to do so.
I could potentially see a hydrogen "battery"/electrolysis setup absorbing excess power in an affordable way, but I'm just saying to date I haven't seen a single one.
The closest thing to a low utilization fuel refinery is probably some desalination plants. Very high energy costs + wild demand swings means some shutdown quite a bit.
There is a few some hydrogen manufacturing plants which only operate on very cheap renewable electricity. However, as I understand it those are currently operated as relatively inexpensive test facilities.
But sure, if hydrogen can be used, stored and then consumed then I can't see why it couldn't be a good idea, assuming demand. The thing about making petrol and diesel is that there's a guaranteed demand for the product, assuming the price is right.