There have been multiple articles and videos circulating on the Internet claiming that optogenetics has made it possible to have perfect input/output to the brain from a computer. This is obviously false or someone would be making a lot of money selling this.
Consequently, I'm curious as to why this is false. Why does having the ability to fire and read the firing information off of individual neurons not imply that a seamless human-computer interface is possible? I'm assuming that this has something to do with the limits of the processing power of our brain and the limits of neuro-plasticity, but my experience in this domain is limited.
If this question is too broad (and I think it is), it can be reframed as a request for references. What current research is being done on this problem? What are the current approaches? Who is working on it? Are there any publications that nicely describe the progress in this (hypothetical) domain?