Those are just time series of wealth over time, they don't purport to establish any causal links. You can't conclude that computers didn't "actually benefit the average American financially" from these numbers, because these are measuring the total wealth of the household with all factors combined. We can't say with any certainty what effect computers had on these values; maybe without them people would have been better off or worse off.

It is interesting how the wealth concentration started in the '80s. It could be computers that caused it, though I would be more likely to blame it on Reagan's economic policies.