I think the confusion is that there are two well-known subgroups of cannabis sativa, indica and sativa (ruderalis is more obscure). So the species and subgroup have the same name, to the consternation of indica lovers.

It may also be referential to the greater indica/sativa internet drama, there are fierce disputes about the differences or lack thereof. The confusion is amplified due to the lack of quality control in cannabis genetics and sales, and most strains are hybrids between the two (or three)