People use glue, pocket joinery, and straps all the time to make box lids, table tops, simple barn-style doors, whatever, without any breadboard edges. My picnic table sat out in the yard for ten years, and none of the boards ever warped or cupped.
evilhorde, IMO you are overthinking it a little. Unless your lumber is not all the way dried for some reason, you should not develop any spots that would be high enough to be fatal to the tank.
Was it pressure treated lumber? Because it sure wasn't the joinery that kept it from cupping. And it's not a "new" problem. It's been happening ever since people made stuff from wood.
I never said that everything needed breadboard edges. It is however a tried and true technique to hide wood movement. There are others of course.
And in some places you don't need to hide the problem. Like on a picnic table. Or barn doors. But have you ever noticed that a solid wood top on a table (like a dining room table) is never glued down. And in fact the screws that attach it are in elongated holes? Or in clips in grooves? That's to account for wood movement.
Dry wood to start is great. But it needs to be acclimated before the first cut is made. And it should be acclimated again after the last is made before it's glued up. Especially if it's been face planed.
If a piece is kept in a home with a relatively consistent moisture level than any warping would be minimal any way.