I think you're looking at it the wrong way. A failed burst, someone escaping successfully, or anything that's not a pure oneshot burst, could potentially have been a kill, but was prevented for varied reasons in each case. Those can be a lot of things, from mitigation, cover, shielding, teamplay, good positioning, defense against peeling, or just somebody defending successfully and suddenly making MP important as a resource. Even with a crushing burst meta, it doesn't absolve everything else either. You said it yourself, assuming no crystal progress is made and nobody dies to negate lb building, it indeed gives no inherent value to the damage that went off for no gain, but it gives inherent value to everything else.

Just out of curiosity, you seem to have played on NA, did you play on EU as well? At high level? Is it similar? Different?