How do you know she doesn't have some other talent that would be squandered if she made a serious commitment to sport?
My mother always thought it was such a pity that I didn't make something of my (modest) musical talent. But if I had I would have been stuck spending hours every day doing something I didn't tbh enjoy all that much- and the other talent I turned out to have would have remained undeveloped.
If your dd has a serious talent and were to take it up, she would need to keep up the kind of commitment expected by the most dedicated and passionate people in the world. This is not the same as playing netball on a wet afternoon: to enter this kind of environment she would have to be prepared to sacrifice every other interest to her sport.
As you put it yourself: "some of these girls have been training intensively since the age of 10. By 15 they are hardened veterans. They have calves that are as big, hard and muscled as tree-trunks"
Don't for a moment imagine that they would expect any less of your dd once she was in. If she has extraordinary talent, they would expect her to do an extraordinary amount of work. And that would be work she would not be putting into her studies.
To do sport, or drama, or music, or dancing, on a level to keep up with the seriously talented, you need almost total commitment:
you need to put all other hobbies and interests away
you need to tuck your social life away in a drawer
you need to work until you cry with pain and then stagger up the next morning, still crying with pain, and start again because it's all that matters to you in life
you need to be prepared to put everything else (including academic results) in second place
you need to demand of your family that they, too, make this their top priority and that everything else has to give to make sure you get to training sessions, extra training sessions, matches, regional competitions etc on time
I am beginning to accept that this is the kind of commitment that my dd has to drama and that in her life everything else is going to have to take second place because it is all that matters to her. But I would never dream of asking it of her if she only had the talent and not the passion.
When your dd applies to university, they won't be interested in whether she has represented her county at an unrelated activity or just thrown a ball around in the park. All they will want to know (apart from exam results) is whether she has shown passion for the subject she is applying to study.
If she applies to read English, they'll want evidence that she reads extensively and can discuss books, if she wants to study medicine they will want to see evidence of e.g. volunteering in caring jobs. There is nothing that looks worse in an admissions interview than a student who manages to convey the impression that "I'm only applying because I have to do something academic but really all my interests lie somewhere else".
As for life enrichment, that will only apply if she actually thinks the commitment is worth it. My dd doesn't care about whether drama will make her rich or look good on her CV because she loves it enough to take risks for it. That is enrichment. Spending hours every day on something you are not particularly fussed about because other people tell you you should doesn't sound terribly enriching to me.
My mother spent a lot of time making me try different instruments because I had some basic talent and she wanted my life enriched. What she missed was the fact that there are many ways of enrichment and I had other talents and interests that could have been developed in that time instead. She sees the missed opportunities in that I didn't pursue music. I see the missed opportunities in that I could have spent those practising sessions developing my real interest in reading or wildlife watching instead.