Think about how we help kids learn to read.
We don't rely on reading the words to them, or with them. We put a finger to the page, and sound the words out with them.
Because without doing that, there's a danger they'll learn to "read by memorization."
Take the word "blue."
It's one thing to be able to see "bl" and say bull (pardon the attempted phonetic spelling). And to connect "ue" with the sound oo.
Thus creating the sounds to pronounce "blue."
And it's a different thing to see the word "blue" on the page like a shape. The same as one might see a circle, square, or triangle. And associating that shape with saying the word "blue."
The first way sets kids up to read on their own. The second sets them up for nothing more than recognizing the word "blue" by its sides, edges, and curves.
This happens in music all the time. Left unchecked, kids form a habit and cycle of memorizing that becomes nearly impossible to break.
Rather than understanding what's on the page, they will learn a tiny bit, memorize, learn a tiny bit, memorize, learn a tiny bit, memorize.
They may get away with learning one piece like this.
But over time, it becomes a torturous, long process to learn any new piece of music. Sightreading music or playing with friends becomes harder and harder over time. And the longer it goes like this, the harder it is to go back.
That's why it's easier to help students read music properly from the very beginning before those habits form.
Eyes on the page. Follow the intervals. Understand what's going on. Don't look at your hands so much.
This is how we do justice to our students.
Otherwise, it's like learning a language by memorization rather than literacy.