That’s a HUGE misunderstanding. That is not even one of the top 3 reasons for doing it. You’re missing out. 
- Devil’s Advocate: The purpose of devil’s advocate, is to test the strength and VALIDITY of an argument. This can help ensure that all potential weaknesses and counterarguments are considered, leading to a more robust conclusion. It helps to mitigate the extremely terrible consequences and deficits caused by cognitive bias and group think. steel-manning another perspective actually helps you and your viewpoint more than anything else you could do.
- Intellectual Exercise: Engaging with opposing viewpoints can be a stimulating mental exercise. It helps improve critical thinking skills, understand different perspectives, and refine one’s own beliefs. It literally makes you smarter over time with huge critical thinking skills that most people are mediocre with. They’ve actually done studies of people who have strong biases on any subject, from political party teams to sports teams, religion, patriotism, even military branches, family, any tribal subject at all or any strong belief someone has. They will take people with opposing views and monitor their brain activity while they watch the same video as the other person, and see the brain literally shut down and not even listen anytime either side is presented with pure facts that don’t support our aid their positional or tribal bias. The brain literally turns off and hears nothing because we don’t actually want to care about facts or the truth or learn unbiasedly. Then the brain will magically light back up and turn on and consume information the moment it starts hearing things that support the biased desire. Most people want to believe this about themselves: “unless you can educate me otherwise.” – But scientific research says it’s almost impossible when it comes to the majority of tribal interactions and premade pet viewpoints that they want to believe. Most people literally cannot hear a viewpoint that doesn’t support their pre-existing conclusion. Their brain literally turns off and doesn’t consider any information that doesn’t boost what they decided the answer should be, even when presented with pure facts. Practicing through intellectual exercise like this is one of the only possible ways to gain skills to protect you from yourself and gain critical thinking. Most people aren’t even capable of deconstructing their own false beliefs and viewpoints because their brain literally shuts off and they’ve never practiced it and can’t objectively tell if something is a fact or not. Some of the research in this area of psychology is wild.
- Fostering Empathy: Arguing from an opposing viewpoint can help a person better understand where others are coming from. This can lead to greater empathy and more nuanced opinions. I can’t tell you how many times, professionally and other instances where I may strongly disagree with somebody, but am able to steelman their viewpoint so they feel understood, and then take that and help them to change their mind once I have done that. By having empathy for their position, and showing I understand by arguing their viewpoint first, they open up and stop resisting and fighting, allowing me to achieve a better desired outcome for all of us. This has made me very successful in recent years.
- Social Dynamics: The last reason, is the least important and is the one that you mentioned above . In some cases, people might argue a point they don’t believe in to provoke discussion, challenge a dominant viewpoint, or keep a conversation lively and engaging. I personally prefer something to this over boring and pointless small talk. But there is a line between asking socially dynamic questions to get someone to talk more or add to a discussion so it doesn’t die out and being a jerk. There is also borderline between the 2 that mixes a little bit of devil’s advocate Ruth pushing for increased engagement.
At least, those are huge reasons why I do it after my psychology education in studying the research on this fascinating issue. I like challenging my confirmation bias and groupthink to reduce the instances of my brain shutting off and not listening to objective data. Not that I’m perfect at this, especially in certain areas/subjects, but I generally try make my brain think and not shut down.
A lot of people legitimately don’t even know why they believe something or what they believe or any foundational basis to their belief. Their belief is purely inherited or tribal from their environment. One of the only ways to overcome that is to steel-man opposite viewpoints like this. If a person doesn’t do that themselves, it’s almost impossible that they will ever deconstruct their false beliefs.