Yes, but multicellular organisms have evolved specifically to contain lineages of cells that form specialized tissue that allows them to better exploit certain

Yes, but multicellular organisms have evolved specifically to contain lineages of cells that form specialized tissue that allows them to better exploit certain ecological niches. These specialized tissues are only possible if the lineages of cells that make up the tissue specialize to a degree that makes them unviable on their own. That is categorically different from, say, a bacterial cell, which is evolved to exist and reproduce on its own.