On the other hand, being thoughtful and competent, but conflict-avoidant, is also potentially career limiting. I say potentially because you can still go quite far if the right people recognize your talent and you develop a reputation for being someone to listen to.
The sweet spot though, is recognizing the power and need for influence, but in pursuit of outcomes, not personal glory. In such a framework your idea is no more valuable to you than any other idea. You also don't need to directly convince everyone of what you know, you can simply make timely observations and ask questions to nudge folks towards the right conclusion independently. Finally, you want to cultivate the humility and self-awareness to realize your own biases and limitations. All paths are tradeoffs, all narratives are reductive and all outcomes are probabilistic.
Similarly, many real world problems lack direct visibility. A person or group may not know enough facts to know what problem they are facing. Ideally, this is a multi-stage problem (i.e. troubleshooting) where you first diagnose the problem and then think about how to address it. (Edit to add: and diagnostics can be iterative, where you have to form a hypothesis and test with a low-risk or low-cost solution to help gather more evidence.)
But, a common group dynamics challenge is that members of the group may not communicate well enough and therefore lack a shared understanding. Once they diverge in terms of their belief about the problem at hand, subsequent debates can become mutually incomprehensible due to unstated assumptions. And, if one member realizes the divergence and tries to steer the group back together, they may face agitated resistance from the members who have already jumped to conclusions as "fact". They may not even realize that there was an earlier starting point and some of their "facts" are supposition...
Hot tip, if you do have a problem it isn't the strength of your opinions and probably isn't your ability to express them either. Assess the situation to see if one of these 3 things hold:
1) You don't have a lot of experience in the domains in question.
2) The conversation is drifting away from how to reliably make/keep the situation good.
3) Multiple people don't see the things you think are obvious and would benefit from someone stating them - but you're focusing the conversation on things you are uncertain about rather than things you understand well.
Picking a workplace classic, someone really confidently starts advocating that we need to migrate the database from Postgres to NoSQLDb. And who knows? Maybe they're right. If you want the play for an unopinionated person it is to loudly say "wow, this is risky but might have a big payoff!", and get a feel for the boss' appetite for risk. If low, talk up all the problems with NoSQL databases and give him cover to say no, or alternative low-risk strategies to try and fix the problem. If high, start talking about ways to embrace the change while keeping risks low (+ make a friend of the NoSQL guy because you're supporting him).
Bam, everyone is a winner, particularly the dude with no opinion. The trap that was set is trying to take a strong position on something you don't understand. Workplace success comes from making the room better just by being there.
You'll notice that both scenarios involve a careful treatment of the risks involved, there is no point in looking for opportunities if the person responsible for choosing the level of risk tolerance doesn't want to tolerate the risk of looking. The only thing being modulated is enthusiasm for leaping into an uncertain situation.
There are some exceptions, though (tabs are evil, etc…) where I have a strong opinion, and sometimes I fantasize about strongly holding it. I am conscious about letting any of those pet peeves become anything bigger.
As of late, I make an effort to evaluate the person in front of me and decide, case by case, if they have enough self-doubt about themselves. Many times it reflects back on my own self-doubt and helps me gauge it.
I've noticed I tend to have more faith in other people's convictions than my own, assuming, essentially, if they believe in something, there must be a great reason behind it
My own opinions tend to be weakly expressed & weakly held. It's usually been good, allowing me to listen and understand others. However, growing in career, I feel my opinions not taken as seriously because the perception of their weakness.
What I've tried, maybe the reverse of it might be helpful:
1. Consciously reflecting that other people have roughly similar amount of self-doubt, even if they don't express it. Even if they present opinions strongly, it doesn't necessarily mean these are right.
2. Lowering the bar for going from 'this might possibly be..' to 'i think this is..' to 'this is..' --- that has been very uncomfortable, and still is depending on the audience.
I love working with peers who don't over-sell their opinions, but have adjusted to have a more equal playing field with those who are more opinionated (both kinds are great people).
+1 to the mention of curiousity elsewhere in the thread - realizing there are many ways to look at anything, all 'right' to some definition of the word based on the person's background and context, can be quite liberating, a fight for being right becomes a journey to understand better how people work.
My 2c, not strong opinions :)