The thing about synapses etc argument is that the hype crowd argues that perhaps the AI could wind up doing something much more effective than what-ever-it-is-that-real-brains-do.
If you look at capabilities, however, it is inarguable that "artificial neurons" seem intrinsically a lot less effective than real ones, if we consider small animals (like e.g. a jumping spider or a bee, or even a roundworm).
It is a rather unusual situation. When it comes to things like e.g. converting chemical energy to mechanical energy, we did not have to fully understand and copy muscles to be able to build a steam engine that has higher mechanical power output than you could get out of an elephant. That was the case for arithmetic, too, and hence there was this expectation of imminent AI in the 1960s.
I think it boils down to intelligence being a very specific thing evolved for a specific purpose, less like "moving underwater from point A to point B" (which submarine does pretty well) and more like "fish doing what fish do". The submarine represents very little progress towards fishiness.
I suspect that "artificial intelligence" may be a bit more like making an artificial bird that self replicates, with computers and AI as it exists now being somewhere in-between thrown rocks and gliders.
We only ever "beat" biology by cheating via removing a core requirement of self replication. An airplane factory that has to scavenge for all the rare elements involved in making a turbine, would never fly. We had never actually beaten biology. Supersonic aircraft may be closer to a rock thrown off the cliff than to surpassing biology.
That "cheat code" shouldn't be expected to apply to skynet or ASI or whatever, because skynet is presumably capable of self replication. Would be pretty odd if "ASI" would be the first thing that we actually beat biology on.