[LiamPowell]

True, but in that case the fuse only needs to be as easy to replace as whatever else you're replacing. If there's internal socketed components then the fuse only needs to be internal and socketed. If everything is soldered to a board then it's fine to have the fuse soldered too.

Many older appliances did expect the user to put some external bits in that would be across mains, or maybe across a transformer to mains, and in that case the fuse was just as replaceable as the user-provided part.

[regularfry]

The fuse in the plug comes from a history of not wanting everything to blow up in the face of "I spilt my tea into the toaster". Very simple device, probably fine once it's dried out.

But really the value of having the fuse in the plug is that if it blows, the live wire in the cable is definitely disconnected all the way to the wall, so whatever has happened you know as best you can that it's not in a state where it could still get worse.