Well, by that logic then ANYTHING you hit at level 8 will be "gone". And we know that's not true at all.
Not true? How so? Are there examples of levels 8+ being used and the target not
being removed from existence altogether?
Individual objects often simply get "gone" when phasered. Sometimes not, but IIRC never in a situation where we'd know of the set level. High settings in TNG are quoted on occasion (Level 10 in "Aquiel", Level 16 in "Frame of Mind" and "Chain of Command"), and they create holes in dense material, apparently by this mysterious "vaporization" or "continuum disruption" process because the edges of the hole do not get hot or anything. The material is indeed simply "gone".
The one exception to this is listed at Memory Alpha: in DS9 "The Forsaken", the (Type 2) phaser setting referred to as "maximum" failed to penetrate a physical wall with "toranium inlay". This sounds like the material toranium (yes, it's a material and not a fancy shielding technology, as it is a plausible bulk cargo later on in "Second Skin") won't be "gone" with a hit. But technically we don't get to hear what this "maximum" setting would have been - absolute highest notch on the scale, or the highest allowed by relevant regulations.