Because I believe a good portion of what Jesus did on the cross and when he resurrected is the defeat of evil powers, the fact that we don't recognise them and where they still exist and cause harm to people seems wrong... My church is involved with some pastors in Africa. The testimonies out of there are incredible, in part because the evil side still manifests so clearly and everyone knows about demonic oppression and it's effects they also know the effects that Jesus smashing those powers has on their lives.
Discussion
Most of the West is baptized, even if most of the baptized don't practice the Faith any more.
Baptism puts Christ's mark on the soul and frees us from the powers of the devil. The reason we don't see more possessions and such in the West is because of that latent grace of Baptism.
Out in Africa, which is starting out much more pagan, it makes perfect sense to me that the demonic is more visible.
In the west we might be less possessed but I believe we are still harassed by spirits.
An interesting thought about baptism, it is when we identify with Jesus's resurrection so it could be 🤔
Harassed, yes, but they have less power because so many in the West have already been claimed for Christ through baptism.
However, Satan is the "prince of this world," and so he has greater power over the unbaptized by default.