Following my other question "no-anti-altering-failsafe-measures". Please correct me if I'm wrong, one who alters one letter of a Torah scroll invalidates it in whole (שו"ע יו"ד רעד).
But I don't recall a special Torah prohibition to do that (see Rambam Hil. Sefer Torah). This seems suspicious that G-d "didn't mind" the Torah be eventually altered (maybe it follows the approach of "דברה התורה כלשון בני אדם" that it does not matter as long as the meaning stays the same). I would expect it to be in the first Mitzvahs to [try to] prevent any future arguments.
If the Torah does not contain any anti-altering built-in measures and there's no prohibition of altering it, what, besides one's conscious, would stop people from altering Torah scrolls?
So why didn't G-d include a special prohibition of altering the Torah scroll whether intentionally or not?