There are a few that don't have the filters. If I remember right, the t-maxx tank didn't have one in it nor did the LST* tank. At least with the LST, they did include an inline filter... unless that was just the old one. Pretty sure my aftershock came with an inline filter because it leaked all over the place until I took it apart and sealed the threads with RTV.
I use them when the tank filter eventually breaks ,but no ,they really aren't needed ,they don't filter out
the fine stuff as good as the rock type filter or what ever its made of!