I asked my daughter the same question and her reply was simply, "I want to play against the best players where ever that is." She's 12.
My daughter is 12, but started playing club pretty young. She loves playing soccer and started playing AYSO, then moved to a local club. All the girls were new, having fun, and just seeing what they could do. Lot's of fun with families and making new friends. It was much more of a "social" thing for all involved.
A few years go by and my daughter's focus/attitude really changed. She was making observations about who the better teams were, which coaches yelled a lot, and which players were a challenge to deal with. She would remember specific girls from teams and point them out when she would see teams at different events. She was also making observations about her own team and the various strengths/weaknesses.
I played a different sport when I was young and played through college. I was very dedicated, but I don't remember thinking the way she does at her age. I didn't get that kind of focus until older.
Last year, when she was 11, she surprised us by saying she wanted to try out for a few other clubs. She had a list! She identified three clubs based on her experience playing against them and getting to know some of the players through other events. After a lot of discussions and a family commitment to support her in this (particularly because we would have to drive a little), she took a spot at a new club on a team that is very good for her age. She has enjoyed the change, although I will note that it is much less "socially" focused than before. She is playing with girls that care about their level of play on a different level than her previous team. It's definitely soccer first and social events second with this group (I suspect that is common). Coach really suits her and so does the team/club/community feel.
Now the club is going to have a DA team and she wants to make it. She has a shot, but not a shoe in.
I have been blown away by this experience. I never played soccer, but her interest has exposed our family to a wonderful sport and we are going along for the ride. However, I know a lot of folks that are making these decisions for their girls. Pushing them, rather than supporting their daughter's own decisions. I also don't think they even recognize they are doing it. But others can see it. There is a pressure on those kids that other players don't have.
Bottom line - if my daughter plays on a team it is because she wants to and we will support that desire.
I share this background because my daughter gave us the exact same reason as yours. Keep in mind that she isn't aware of the whole debate on this forum about DA/ECNL. She simply knows that the DA team at her club will be the top team. She has the perception that DA will be for the best players and she wants to play against the best.