I did find this posting from a 2012 thread about the same issue.
"Knitpick to your heart's content. Make sure you go over everything and that it's fixed before you're satisfied, but keep in mind that a certain amount of flex is necessary or the thing will rip apart at the seams. Check out a flatbed semi trailer. When empty, there's almost a foot of "arch" built into the bed frame. When loaded, it flexes to "flat or even more". The same holds true with airplane wings. To a certain extent, flexing is the "shock absorber" of a flat surface.*
On the pedastle attachments in your table, if it were completely rigid, every time you bump against the table, you'd stress the attaching screws, eventually, they would either tear out of the OSB floor or come loose/shear from their mount. Would another type of mounting system be more rigid? Yup, but again, the cost is much greater and the compromise between profit and reliability has to be "juggled" or Keystone wouldn't be in business.*
Without the ability to flex some, the movement during travel and use would all be absorbed by the corners/angles and that would lead to failure much faster than if it flexes to absorb the impact. How much is too much flex? who knows, but it is annoying to have a table wobble at dinner...... There's somewhat of a compromise between engineering, weight reduction and livability."