I am quite familiar with this false argument and Robert Morris is one of the chief proponents. Jesus had to opportunity to discuss this subject in terms of oppressed or influence but instead only discuss it in terms of possession and a demon being in, or out a person. When Jesus or the Apostles discuss it in the non-biblical terms that you proposed then I will listen. This a ridiculous theory espoused by those that want to promote "deliverance." Why? Because they then get to participate in false deliverance thereby boosting their egos.
I am astounded that you advised me to to avoid a word taught by Jesus. Are you sure you want to do that? Better to not go beyond what is written, and avoid non-biblical concepts and words.
You are obviously unaware of the way that evil spirits operate. A born again Christian cannot be possessed. The new spirit is of God and Satan has no access to it. Evil spirits start by attacking the mind (2 Corinthians 10:5). If the individual accepts the thought, the evil spirit will lodge in the mind. From then on, it will influence the individual, extremely subtly, until it has control of the person's will. When it gets to that stage, it has to be cast out.
Evil spirits can also come in instantly. When my daughter was a toddler, we were nearly bowled over by a car that ran a red light. It was terrifying. My daughter had a spirit of fear as a result. I cast it out and she was back to normal. People say that they are addicted to porn. It is a lust demon that they've allowed in by giving into temptation. Smoking is also an addiction that comes from an evil spirit. I've never met one person who enjoyed their first cigarette. There is no logic or reason to smoke. Yet it is one of the hardest addictions to break. I've been told by drug addicts that it was easier to give up heroin.
One of my friends smoked for 30 years. He tried everything to quit. One day he saw that it was an evil spirit. It was cast out and he was free. You won't find a nicotine spirit in the Bible either.
For a much deeper and clearer explanation, I suggest that you read "War on the Saints" by Jesse Penn-Lewis. Derek Prince wrote some excellent books on the subject.