I own a metal one which I assume was dishwasher safe but somehow water got trapped inside the 'extra' parts of it which could be unsanitary due to the water eventually stagnating.
Another is that the heat from the dishwasher can warp and silicone or plastic parts which will render them unusable eventually.
Not saying you're wrong but this is what I consider from the warning they provide.
General purpose silicones like silicone sealants and gaskets tend to have a high-temperature limit of around 200 C to 250 C and also lower temperatures of -50 C to -75 C.
So your dishwasher isn't going to warp silicone, but lots of plastics, yeah.
I've seen a lot of fabrics that say "Dry Clean Only" because the manufacturer was too lazy, but my experience with dishes finds that the labels are generally quite accurate. Putting a non-dishwasher-safe item in usually ruins it.
Well yeah “Dishwasher safe” is an endorsement. The lack of an endorsement is not an endorsement to the contrary. Something is only “dishwasher unsafe” if it says “Hand wash only”