Why no perceptual merging of layers?

Not at all what I'm talking about. Unless you merge layers carefully, Photoshop will never do it right. It will combine layer modes into garbage instead of collapsing the actual presentation of what you see in front of you on to the desired layer. There's no command key to make this happen, Screen on top of Vivid on top of Normal / etc? Merge the Screen and Vivid. Boom, Photoshop it wrong, the layers are merged with no intelligence. This catches every user off guard at some point, and it becomes a serious problem when you're 30 layers in and basically need to stamp the entire image and start over.

But look, twice now you deleted text because it made someone uncomfortable, and yet managed to get yourself two updoots? People have complained about this for ages and worked around it by avoiding layers. I'm surprised you didn't outright edit my response to suit your "whoosh" answer!