The common route is a harem route(again not actually a harem but I don't have a better term for it). Even with the individual routes it's still a harem(you get what I mean) because they don't impede each other with a few exceptions(some make sense, others don't). It just feels like a way for the dev to artificially extend playtime so he has more time between updates which I get but also considering the purpose of a game is to be enjoyable this is an impediment.It doesn't lead you on, at no point it promises you any sort of harem route. Having shared "common route" which eventually splits into individual path(s) for the girl you pick is a very common approach to VNs. Though admittedly this is more common for Japanese games than the Western take on the subject.
EDIT: Let people have a choice is all I'm saying so you don't force them to make a choice they don't want to make.