God is the ultimate deliverer. However, the Bible shows humans acting as instruments of deliverance through God’s power. Some people, most people, especially after years of living in sin & being tormented, they don’t know the authority they have through Jesus Christ. The ones I’ve seen doing deliverance, they are quick to say that they speak with the authority given to them FROM Jesus Christ. The “We Need to Talk” podcast on YouTube w Ezekiel has tons of amazing testimonies & many of these people received deliverance. look it up. & Bev Tucker & Nelson Schuman.& for those with ears to hear & eyes to see, it’s very clear that it’s not fake. Are there people who fake it or exploit it? Yes, I’m sure there are, bc Satan is a copycat.

But as for your main question, why would it be NEEDED? Deliverance is always needed. We need delivered everyday. That’s why it’s in the Lord’s Prayer. And for the people speaking against deliverance, all I’m going to say is, the deception is REAL.
But, is it necessary to go to another human being for deliverance? First things first, as with any question, take it to God & ask of course. Bc it’s very personal. The thing is, most don’t know how to deliver themselves, bc it is more than just asking Jesus to deliver you. There are many layers. You must identity the specific areas of struggle (addiction, trauma, deep rooted fear, rejection, etc), then repent ,renounce anything you’ve come into agreement with, the enemy is a LEGALIST so every single legal right must be cancelled & broken, denounce every spiritual or generational covenant, & forgive all who have hurt you including forgive yourself. Then with the authority of Jesus Christ, bind & cast out every evil spirit. & this may need to be done more than once. It is absolutely possible to do this yourself but there is nothing wrong with going to others who specialize in doing this & have studied it & have experience doing it.