Players not buying items??

Throughout quite a few games I've played recently I've noticed that some people haven't been buying anything from the shop through the entire game. They cause feeding for the other team and are making it unfair for their team. Is this some kind of bug or are they trying to troll everyone?

Not sure if it's relevant or not but i also noticed that everyone who has done this has only used the skills Barrier and Cleanse. In an Aram game that makes no sense. I've seen this happen in one classic game and several Aram games. On some occasions it's more than one person.