I'd guess they are intended for such as the inputs to small switch-mode PSUs, where they need to stand the initial capacitor charge current when power is connected, but still blow with a sustained low overload.
The price seems low! I've found those at $16.75 per hundred; checking prices for all time-delay fuses on Mouser, that puts them third cheapest out of all (near 3000) 250V AC rated ones.