Now, these are two arguments I don't like.
First one. People who have followed City through three divisions aren't going to stop watching if they think there is an attempt, at the moment, to stop us winning trophies, especially as it doesn't seem to be working. It's the "participate in society" meme.
Second one. I doubt anyone really believes the PL picks who they want to win the trophy before the season starts. But it is in their interests to i) keep it close ii) keep the most supported teams at the top and iii) to have new names up there sometimes. It would be naive to assume they don't have these objectives. That doesn't mean they will will ensure that key decisions are given wrongly, but it can mean that games and teams are refereed differently at different stages of the season.
Personally, I don't see any malicious intent to damage City's chances, but I can imagine that some games are refereed differently to others. I think we have all seen that. And for the reasons I set out above.