Octalink is proprietary to Shimano and I think it came out in late 1990s or early 2000s. I bought a road bike in 2003 that had Octalink. The interface between the BB spindle and crank was much better compared to the square taper it replaced. And it probably reduced the weight of the spindle. Octalink died when the 'next best thing' came out, external BB bearings, which allowed for a much stiffer BB and an even larger diameter BB spindle. Then that of course was dead when they came out with pressed in BBs.........

There's nothing wrong with Octalink, it just means you're probably mating it to a 8 or 9 speed drivetrain, which in itself is not bad, but now there's 11 and 12......