This matches my experience; I think some Kijiji sellers do get haggling fatigue after a while, where they've dealt with one too many tire-kicker types who show up offering 50% (or less) of the listed price. Or play other games, like agreeing on a price and then showing up short of cash and making a scene about having to drive back out and find the nearest bank machine. I had this happen once and stood my ground over it; suddenly the missing $20 miraculously appeared with no ATM trip necessary.

Anyway, being able to advertise a price as firm does provide a convenient escape hatch in that scenario.