Sometimes we say things in order to help students do the math rather than understand the math. Those statements can create misconceptions and confusion when the statements no longer hold true at later grades.

When does it fall apart?

When students are subtracting 125 - 17, they may think they "don't have enough ones", when in fact, they have 125 ones.

Why?

Students have not learned to distinguish between "there is a 5 in the ones place" and "there are 125 ones".

Instead say: 

Reinforce the idea that 125 has 125 ones, 12 tens, 1 hundred, 1250 tenths, 12 500 hundredths, etc.