Seems likely too that the collection of rags and bones (for their various uses) became more systematic, with rags and bones as side-products of industrialised processes, and therefore collecting a few rags and bones from individuals was no longer economically worthwhile. There are also other ways to make money now, that are more profitable to the individual than collecting bones worth a few pence per bag.
I suspect too that the rise of plastics mean that we have fewer day-to-day uses for bones, as handles for things, ornaments, etc. This leaves only the larger scale industrial uses, that get bone from other industrial food production processes.
The article mentions that Rag & Bone men moved to items that were still valuable e.g. scrap metal. They weren't chased out of neighborhoods.