It's still hard to produce photonic circuitry at the complexity we need for CPUs and such.

Graphine and nano carbon and carbyne and whatnot? Could be what we need to produce a post-5nm IC fabrication technology for manufacturers.

Well, yeah, but it's still hard to produce graphene circuitry at the complexity we need for CPUs and such, too. Are photonics actually harder?

A bit harder, yes.

my understanding is that the wavelength of light is a limiting factor in photonics.

There's more interference.

That's an area of very active research, it's not like people are ignoring it. And it's just starting to bear fruit.