Where we live, that is middle class. Median household income in our county is $125,000 and the average age here is pretty young. We fit the numbers you said above and then some (two incomes plus navy reserve retirement pay), but I am 57 and DH is 60, we're at our peak earning time, and our kids are grown, and we have spent years getting to this point. We live in the wealthiest county in the US (it's always #1 or 2) but the cost of living is very high. That's what people don't get. If you make $100,000 per year but live somewhere that homes are $200,000 you already have a higher percentage of disposable income than we do. Our home cost us 5x what we were making when we bought it. It's currently worth 3x what we make now. Are we fortunate? Yes, but it didn't just happen. We also spent years when I was a SAHM just making ends meet because of the high cost of living in the DC area. What's funny is we are doing well, but we have neighbors who make more than we do. All it takes is two GS-14/15 (Fed gov) to hit $300,000 household incomes which I know quite a few who do. These are people with advanced degrees and/or technical degrees and backgrounds. Our house is large, but we have communities all over the county with larger ones.
There's a lot more to look at than just the numbers you stated above. You can't just make the statement you did because you "think" that's not middle class. While the national average is well below that, it fits our location.