I can't take the "Sonic is a big brother who raised Tails" rethoric seriously because we have better examples of this dynamic in fiction between different species: Finn and Jake, for example. In this type of situation, the big bro acts like a surrogate father, doing what a parent would do: Jake cooks for Finn, emotionally cares for him, saves him etc. Not only Tails is completely independent, but he's more responsible than Sonic.