I've noticed amongst some of my friends with similar issues that they see disagreeing as being a kind of harm. That to make someone uncomfortable or upset is as bad as kicking them in the shin or yelling at them.

You can't feed a child nothing but candy. Candy is delicious and great, I love candy, but it's just sugar. To merely agree with someone all the same is to both undervalue their agency (what makes them human, their ability to engage critically and freely with new information) and over-value the norm. In other words, to agree with someone all the time is to give them nothing but sugar candy.

That's not license to yell or be a jerk. Please don't go around trodding on people and calling them sheeple. But do disagree with people because it both helps you and betters them. To engage with opinions we don't have, to consume information we don't like is the intellectual equivalent of eating your vegetables.

Saying no or directly contradicting is often not necessary. Often the reason you might be interested in saying no is a value or dynamic you feel is being under addressed or undervalued. You can compliment what's positive in another's statement and ask about that positions relationship with the value or dynamic you identify as needing to be addressed or valued.

Oh man, it's made me a god damned jedi master of doing that. I'll jump through all the hoops and contortions to avoid a really direct contradiction. I think I'm actually pretty good at getting to consensus as a byproduct of stubborn "must be right" and avoidant "must be liked."