Not at all! There's a whole thread about this in the CPS2 forum as well.
In fact, I recently got a Jojo Heritage with a battery from roughly the same date range (1997), still worked. Swapped it to a new battery immediately. That wasn't the first one, either - I've gotten a hold of several Third Strike carts in the last few years that were still on their original batteries.
I think it has a lot to do with how long the cart was in use, and not just sitting on a shelf, as well as the storage conditions. I imagine going through extreme weather cycles in Japan without HVAC likely does a number on these, whereas the ones that are stored in climate-controlled conditions likely last a lot longer.