Well, if you want to know whether neural nets are in their "infancy" you shouldn't make "observations", you should read the literature. It goes back many years. Go to the primary sources, why try to guess and risk guessing wrong, as here?
>> I stand by my claim: "neural network architectures are still in their infancy, it is very likely that more efficient approaches exist".
Half of your "claim" is incorrect. Don't just double down on it! There's really nothing to "claim" here, the "infancy" or not of neural nets is not a matter of claiming or guessing. Either you know what it is, or you don't.