A beachcomber typically wanders along the beach looking for anything discarded or washed up.
Most of the material on the beach is rubbish, some has been intentionally abandoned and some long lost, so the beachcomber is not taking anything that belongs to or is valued by anyone else. In fact the whole practice is simple recycling and is an economically valuable function.
The French word for beach is “plage”, so we might expect the beachcomber to be called a “plagiarist”, but that carries a whole new wave of meaning. A plagiarist takes words he finds washed up on the silicon edges of the information ocean and recycles them. But these aren’t abandoned words and texts. They belong to their authors and that ownership is protected by law. The creators of the work are often damaged by the appropriation of their writing.
The crime is worse because the plagiarist then attempts a fraud. He tries to pass off the stolen words as his own. This may be a trivial issue when one person retells another person’s story over dinner, but it is an unforgiveable crime in an academic context. The academic world judges its citizens by the quality and impact of their writing. To steal that writing is criminal but to use stolen writing to gain points, recognition or certification that have not been earned is a fundamental breach of trust.
Some aspects of plagiarism seem harmless enough. A simple quote from one source, but without acknowledgement, is hardly a capital offence.