After I have seen a lot of questions here using the DATE_SUB() or DATE_ADD() functions instead of the arithmetic operators + or -
For me, it is a matter of experience. After dealing with multiple editors, libraries, and tools that manipulate databases, I've learned not to trust the "+" and "-" operators as much as I trust DATE_SUB(). It's a lot less likely that something is going to be accidentally broken as part of the next software upgrade with DATE_SUB(), when compared to using +/-