It still drastically narrows down the search space and makes social engineering a LOT easier.
Because you tend to have one of two sources for any password that people need to remember.
Randomly generated with no rhyme or reason. And written down on a sticky note as a result
Something with meaning to the user
And it is the latter where this becomes an issue. Because let's say they are a 50 year old and 1, 4, 6, 7, and 9 are heavily worn. Well, they were born in the 70s so let's verify exactly when. Hmm, May. No 5 means it probably isn't their birthday. Wait... their partner was born on April 7th, 1976. No luck. Oh, but what if they were clever and it is actually 197647 instead of 471976? Boom, in.