hmmm i dont mean they are the same, but they explore some similar if not the same ideas, but each with their own ontake and level of focus/priority
season three did imo explore idea of relationships with people quite deeply
analogy...an idea/focus (in this case its relationships with people) can be clay
the anime is what moulds it
Aria moulds its into something "warm and fuzzy"
5cm moulds it into something "cold and sad"
of course you're entitled to your opinion if you disagree, but i do feel that the theme is quite firmly addressed in Aria