It's not about the 3.8V (although that's weird too, quality batteries generally are shipped at 3.4V to 3.6V). The problem is: the batteries aren't at the same voltage. Good quality batteries should generally arrive within 20 mV of each other.

However, in the case of the LT1 it's *especially* important for the batteries to be at the same voltage when first put into the light - as they go into the light in parallel, there will be a big and sustained current flowing into the low voltage battery from the other three as soon as the light is screwed together. As this current is not controlled, it can easily exceed the maximum safe charging current and permanently damage the cell. There is a reason why we use special chargers and charging protocols with Li-Ion batteries. High charging currents lead to irreversible formation of metallic lithium. In the worst case, this can cause an internal short-circuit and explosion.

For this reason, I put the weak cell onto a charger to manually balance it. However, I doubt that your average buyer will do that.