It's intuitive.
Is it? The DIL device scores by being able to have its legs bent over and soldered down on the other side of the board. That isn't going to come loose too easily. OTOH the SMD device is held on solely by the strength of the glue holding down the tiny pad. Levered with a screwdriver, as a test, I know which will come off first 
You might use glue, the rest of us use solder. This may also be a clue as to why you've been having difficulty getting SMD stuff to work.

But seriously, brazing/soldering about 50% of the area of a very light part (~10mg for a DHVQFN16) to a board, as compared to suspending a heavier part (DIL16 1100mg) off the board on flexible metal legs it
is intuitive which will be stronger, unless one has no mechanical intuition. Similarly the service loads on parts are a result of their mass being accelerated and decelerated, not some gorilla deliberately attacking them with a screwdriver.