Go to any University in our country. Then find the music program building. Search for the practice rooms, and who do you find in there?
Not usually vocal students. Emphasis on "usually." This blog is not claiming any universal truth, but a general truth about many vocalists. If you are a vocalist who doesn't fit this picture... good for you, I guess.
In the practice rooms of universities you may find a pianist, a trumpet player, or any variety of musical instrumentalist. The vocalist however, is somewhere having a good time taking for granted that he/she will be able to nail their part because they "already know how to sing."
This is why vocal students don't go anywhere with their skills and talents. It's raw laziness. They have been told all their lives how good they are and when they sing, it often comes naturally. Sooooooo, they don't push themselves. They are often content to be simply "good enough." This ends up forming some pretty nasty habits. When someone is content to stay where they are with their abilities, they are basically admitting they have peaked out. Like a business that had some cool ideas and then stopped being innovative. What happens? That company declines in relevance to the public eye.
A similar thing is true for vocalists. When you don't expand your abilities, you start to look like a one trick pony. You have shown us all that you have to offer and once we have seen that concert, there's no need to see it twenty more times.
The point in all this? Practice helps expand who we are as musicians. Don't stop expanding who you are. Practice.