It seems to be a flaw in both the hardware and software side of things. Hardware wise, we have yet to make chips that achieve the processing density of human brain matter. Also, heat generation becomes an issue as you try to scale smaller systems up. Software wise, we know our current neural networks dont scale up well, so we seem to be waiting on some more foundational research for more efficient algorithms. My suspicion is that we're not really going to get true General Superintelligence until we start manufacturing chips that incorporate living neurons, it just really seems cheaper to use already existing computing systems than to design your own architecture.