As i already said it is to satisfy compliance and the loads are unlikely to blow a fuse but the customer wants one. So a fuse they get that will never be needed but it's there.
No, "the customer is always right" does not 100% apply to engineering. The customer does not know the safety standards, or have experience doing product development. Blindly following what they want can be a noose around the engineer's neck. You have to explain and negotiate the product's requirements with a customer, sales/marketing, upper management etc. Sometimes you have to firmly say "no" to their demands because otherwise you end up making something unsafe or unreliable.
If you use non-replaceable fuses, your product is only as good as the fans.
A lemon fan- mosfets that short, bearings failing, water getting in, plastic blades cracking and flying off- mean overcurrent and your fuse pops. A guy puts a new module in and it also pops a fuse. Hmmm. I have seen this, and by time they figure the (fan) load is the problem, there is a box of dud modules needing costly repairs at no fault of the module.
I would also question say 4 of 20A fans and 80A feed for a board, it's not practical due to the heat generated by connections, pcb traces, and components. I had a hard time designing for high ambient temperatures with high currents and potting. I don't know your details but be careful you don't make a silly product. Something that fails a lot can sink a company.
Possibly an electronic fuse by monitoring load current, and MCU with trouble codes would be better.