Not all, but many Mongoose bikes, and almost everyone you will see in a bike shop are entry level bikes. Mongoose has more recently been way behind the curve on putting out decent entry level bikes.
Now, if you are looking at Wal-Mart for a bike, go buy some diapers instead.
The first rule of bmx should be this: DO NOT BUY YOUR BIKE WHERE YOU CAN BUY DIAPERS!!!
What does Wal-Mart know about bmx or quality bikes?
While your old bike may have lasted five years, jumping stairs is not the type of thing that would kill it. But, a few harsh landings off a box jump, or jumping 10+ steps likely would have. I saw a kid who could absolutely kill the box jump on a Wal-Mart Huffy... then he landed a bit off once and the frame snapped and he was taken to the hospital for some stitches. The bike had been fine the last ten times he was at the park and the prior year he owned it. But, that day the cheap bike took him down.
Their Team Issue bikes aren't bad, but still are running Tektro brakes and non-chrome rims. So, even on their 'high-end' bikes, they are cutting corners and doing stupid things. That is consistent with what Mongoose has become.