It's impossible to know without seeing the circuit.
As you said, thermal stability will be a reason, since there's less self-heating.
It would make sense for high value resistors. Higher values are difficult to make with a close tolerance, so need to be larger, like connecting lots of smaller, lower values in series, but you said they're just 47k, which isn't that high.
I also think lower noise could be a reason. Noise averages out, so making something larger aught to reduce the noise.