Should brake fluid be changed on an old truck?

Took my 2005 suburban for an oil change
and they suggested I change the brake fluid
because it is dirty. I just had the brake pads
changed by another mechanic so I decided
to ask the brake mechanic what he thought.
He told me that good mechanics never
change brake fluid on an old system because
“that’s when things start going wrong.” He
said they will only top it off. He told me the oil
change mechanic were only trying to sell me
something and didn’t know anything. I do see
his point, but I also find it hard to believe I am
never supposed to change my brake fluid
because my truck is old.