To put the errata into context: It's not a fix afterwards to balance out the rules, it's a fix afterwards to clean up a printing mistake. During playtesting many variants were used, and here and there in the rules they didn't properly clean out some of the variants. Take Lifestyle/Gear costs for Dwarves & Trolls, Connection as dicepool modifier or limit modifier, and so on. The karma cost for Power Points is the same, it was never intended to go to print but they missed cleaning it out.
My memory may be failing me, but I vaguely recall that this was a day-zero errata so to speak. Developers acknowledged it was a mistake and quickly provided the correct value even before the PDF was released. This was in part possible because the incorrect value was noted in one of the SR5 Previews, and in part because of the time between being sent to the printer and coming out in PDF form. So basically very since SR5 was actually out, it's been known to many that it should be 5. But since the errata took a while, only the Mission Hotpatch Errata noted it for people to find.