In a brief, the resistor is only useful for OPs with bipolar transistor input stage that don't utilize input current compensation. It's degrading performance of MOS or JFET OPs (increasing noise) and also of input current compensated amplifiers (Ios has the same order of magnitude as Ib, any additional input resistor typically increases overall offset and offset drift).
In other words, it's a typical element of OP circuit designed in the sixties and seventies. People are copying it from text book circuits without understanding why.