It's a bit like sixth form college. That's the school you used to go to after you'd finished five years at secondary school. But in 1990-ish they changed the numbering scheme. Now the year number is the number of years you've been in education. One for your first year at primary school, eleven for your last year at secondary school. So now sixth form college is where you go after you've finished year eleven. But it's still called sixth form college.
I'm also reminded of something Jerry Weinberg wrote in Experiential Learning - Vol 3 Simulation.
Rules are frozen solutions. Rules are solutions to yesterday's problem, carried forward to the present, but usually without reference to the problem they were intended to solve. Each rule is really an "if-then" rule, but the "if-then" part is seldom stated.
If you don't know why you're putting eye-of-newt into the cauldron then you're in trouble when the magic potion stops working. And if you don't understand why eye-of-newt works, you'll probably be afraid to change the recipe.