I think that is fine, and the usual recommendation.
My daughter's Teacher's grandson, had the same recommendation as your child. It helped him.. he had, in class, a Speech Therapist work with him. It helped.
He had articulation delays too, and speech delays.
My son, had that too. And speech therapy from 19 months old until almost 3 years old. He was speech delayed and had some articulation problems. But he was also advanced in several areas of development, for his age. And he is bi-lingual.
Keep in mind that "articulation" is an age based development. At each age, they 'can' pronounce certain sounds and not others. But, the Speech Therapy will give them tools, to improve that. And for the parent, it gives you tools/information to help with it too.
There are front of the mouth sounds, back of the mouth sounds, and some sounds that are harder because it requires mouth/tongue/throat coordination to pronounce certain sounds/alphabets. So, at each age, a child is 'able', developmentally, to attain these sounds from their mouth.
No, I don't think you are going overboard. It will help.
For my son and the grandson of my daughter's Teacher, it was all free... through our local Early Childhood Intervention program. So, why not? Take advantage of their services.
As the Speech Therapist told you, it can't hurt.
Sure, she may grow out of it... but when?
And assisting a child, for speaking or articulation, is beneficial. And for the parent as well, to learn about it and speech development.
I learned TONS from our Speech Therapist, about speech in children.
I would go for it.
It can't hurt.
Do it while you do have the services available to you, and while she is still young.
My son, is 3.5 now, almost 4 years old. He is the most talkative one in our family now. He still has some lingering articulation issues.. .but I now know how to help him myself. And he LOVED his speech therapy and how it helped him.
all the best,
Susan