The agreeing part does not have to mean you then cannot disagree in the very next sentence.

Remember this is about learning to get better people skills. Being approving instead of denying is a huge part in that.

Many people deviate to "No" so quickly that they just become Nay-sayers. This is a tool for you to change that.

That being said, you do not have to agree with literally everything. If someone asks me "Don't you think war is good?" I will likely not agree.

But, and this is just to play Devil's advocate, if you do agree you put yourself on the side of that person. From that side it will be much easier to argue, hold a conversation and openly discuss.

Think about some fanatics, be they religious or otherwise, and consider what would happen if you agreed only to open up the conversation.

It is a slippery slope for sure, but a lot of advices I share can be horribly misused. That is all of Psychology.

That being said I trust in my readers to use them in the right and responsible ways.

It is a bit hard to explain all of this via text, but the main point to agreeing with someone is so that they do not get into a defensive mode which would block out almost all attempts at an actual discussion.