Kylo Ren and Snoke act exactly like Sith, though.

I’d argue they’re Sith of a non-Baneite lineage, but I’m sure Canon will contradict me on that.

That’s why I don’t take “I am all the Sith” literally.

I believe this is meant to symbolic.

You can interpret it however you want, but the intended meaning is 100% that Palpatine is possessed by the spirit of what I can only assume is Darth Bane, not that Abrams or Terrio would know that. Point is, the stuff about essence transfer and “make the sarcrifice” clearly lays out the idea that all the Sith up to Palpatine are just the same guy body hopping…or something. It’s definitely not intended metaphorically, as much I’d prefer it to be.