Most of the batteries I've run into that come dry are automotive / power sports batteries. Specifically, motorcycle and UTV batteries.
There are lots of factors that affect lead-acid battery aging. Unfortunately, many of them are non-recoverable like degradation of the battery plates. Only fix there is new plates (old-school batteries had much thicker plates and thus this was less likely to be the reason they stopped working). If you've still got enough plate, no internal shorts, and they aren't covered with sulphate crystals, new electrolyte could help. Some chargers have modes to help break up sulphate crystals to extend life. Making sure you don't abuse (overcharge or overdrain) them and keeping the water levels topped up with distilled water is the best way to prolong their life, but once they're gone any extension of life is on borrowed time.
Unfortunately batteries are generally a limited-lifespan product.