I believe this is true. I know from my learning about my Kegerator that an untapped keg goes bad after 8-10 weeks, and it has to be kept refrigerated the whole time or it goes skunk. Once tapped, you have about 4 weeks to drink it, and it has to be kept under pressure from a CO2 tank. I use 5-gallon kegs, called a "1/6 barrel slim." A Pony Keg is a shorter and fatter 1/4 barrel, or 7.5 gallons.
What most people call a "Full Keg" is actually a half barrel, or 15 gallons. That's the size they use in bars.