There is also a blower resistor that sits under the fan. It must get pretty hot seeing as the heat sink is the size your foot. Fuse blowing caused by too high of resistance. Resistance can be from both fan motor bushings as well as overheating resistor.

If you go in to fix the blower fan, you may want to replace the resistor while your in there.

My blower was inop, but the fuse was good/blown resistor. BUT, fan was hard to turn so it probably cooked the resistor.

They use bushings because they are quieter than ball bearings, and do generally last a very long time. But I agree that sealed ball bearings would probably outlast the bushings. Still, this car is 23 years old and all the fan needed was some ATF on the bushings and away she flew.