To make it accurate, it would be like if there was only one store you could ever buy things from and that store had a limited number of shelves, and someone came along and wanted to use up one of the shelves that to sell an old tool that few people need, and they also only accepted a weird form of payment that would randomly cause issues with some people.
I think we're getting at the heart of your misunderstanding. You seem to feel that we're running out of codepoints in Unicode (the “limited number of shelves” analogy). This could not be further from the truth. Although the number of codepoints is technically finite, it is extremely large (over a million) compared to how many we need (currently only 160,000 are defined, and for obvious reasons the rate of new additions is slowing down). The Unicode roadmaps main page[0] displays only 5 of the 17 available planes because the remaining 12 (each 65,536 codepoints large) have not yet had any characters assigned to them whatsoever.
To make it accurate, it would be like if there was only one store you could ever buy things from and that store had a limited number of shelves, and someone came along and wanted to use up one of the shelves that to sell an old tool that few people need, and they also only accepted a weird form of payment that would randomly cause issues with some people.