Ok, when you look at it like this, what physicists are seeing is the first two 1s and the 3, so seeing 1+1 = 3 in nature, and it obviously looks wrong to you, yeah, you try to figure out why it's there: either (a) we don't understand math, or (b) we missed something in the equation. Occam's Razor says we missed something in the equation. So we add another 1 to make it make sense for now while we look for proof that either (a) or (b) are true.

You can also do math like a theologian 1 + 1 + god = 3. Or even simpler 3 gods = 1 god, so 3 ~~gods~~ = 1 ~~god~~ therefore 3 = 1.