Unfortunately, sometimes salespeople don't know or they're just trying to make a sale.
There's plenty of info here on MNL and it is known that Leafs built before 4/2013 have crappy batteries in terms of degradation. We have no idea how many bars it had when you bought it and whether you'd get to 8 bars in time, which is mainly influenced by climate.
If you had monitored battery status via Leaf Spy, you could've asked around and possibly taken actions to speed up degradation to make it hit 8 bars before capacity warranty expiration (e.g. leave at 100% charge in the heat, ship car to Phoenix, etc.)
nbeker wrote:I have Nissan Leaf 2012 out of warranty,4th bar dropped in 5 years and 5 months, 37000 miles.
Why they did not replace the battery before 4th bar dropping under 5 years wattanty?
Because the terms of the capacity warranty at viewtopic.php?t=13192
In addition to the existing lithium-ion battery coverage provided under the Nissan Electric Vehicle Limited Warranty for defects in materials or workmanship, the lithium-ion battery for your 2011 or 2012 Nissan LEAF is now also warranted against capacity loss below nine (9) bars (or approximately below 70 percent) as shown on the vehicle’s battery capacity level gauge for a period of 60 months or 60,000 miles, whichever comes first.
You lost it 5 months too late. The capacity warranty expired by then. Nissan wasn't legally obligated per the warranty that came about due to the Klee class action lawsuit settlement to help unless you lost the 4th capacity bar before expiration.