I think that there is as much evidence to show that children benefit from a later start to academics as an early start. I think its one of those areas where researchers tend to look for evidence to prove their beliefs. I would go with the Montessori theory of 'follow the child'.
Presumably parents who use the Suzuki method think that there is some benefit to starting early. However, I would imagine that it is very hard to tell whether children who start early on the violin make better progress than other children who have equally involved parents but don't involve them in formal music till later and/or give them lots of informal musical exposure, because the bigger influence on all these children is parental support and a stable background.
On the other hand, I find it hard to believe that it does a 3 year old harm to learn the violin, or that a 3 year old who hated to play the violin could be cajoled into it.
Similarly, I think there is little evidence to show that a child is better off being taught to read at 4, 6 or 7, although many children are ready to read at 4. (Although I would imagine that not being able to tick the right boxes in school as dictated by the government might put you at a disadvantage.)
I think the biggest influence on success is having loving, confident parents with high expectations and enough food on the table and a roof over your head. After this, a child can do equally well with parents who spend their weekends playing football, reading, getting their children to do extra homework or building dens.
Interestingly, talking of books that get articles about them in Sunday Papers, Sheryl Sandberg argues in 'Leaning In' that girls do well at school because they are 'good' and try to tick all the right boxes because this is what the prevailing culture tells them to do, then fail in the work place, because, after all other skills (taking risks, taking on work that is beyond your current competence, talking confidently) are more important.