I just completed a keyboard build, skipped stickers this time, as it seemed like they don't contribute much (I 3d-print my stickers, I could have just printed some more or use the ones I already have, why didn't I? ...)
I feel like I built a car and didn't install gaskets
I skipped them as I verified they don't prevent side-wobble, when you put switches on square cutouts, the switch can't wobble sideways, yet I obviously didn't check for vertical wobble, it turns out, they mainly prevent the vertical wobbling(duh, since the switch top has front and bottom sections that lets the stem slide, it mainly provides front/back support, the wobble happens on this axis)
The switch enclosure also sometimes produces a small click sound during this back and forth vertical movement, as the switch top re-seats
I'm sure practically the difference is small, most probably not noticeable as this mini-click/re-alignment doesn't occur when typing, yet the moral of this story is, better safe than sorry, install your stickers
I guess I might re-build at a future point in time, install those plastic gaskets, maybe if the switches gets loose in future