I wouldn't say I have ever been too agreeable. I've never been afraid to disagree, in fact i've been called out for being a contrarian, so maybe i'm on the ever end of the scale to how you were. My brother is someone who finds it extremely difficult to say no to people and I've lost count how many times he's upset people for not following through on his words/promises. And then there are the people who are so agreeable to the point that they get walked all over.
While i'll be maybe arrogant enough to say I know what good communication is, it doesn't mean that I'm good at it. I believe it's a practice. As much as I would love to start a podcast or make content where I improvise speech, I find my stream of monologue to be extremely shaky. I am good with face to face interaction, but I notice a big difference when having faceless internet conversations. Maybe it's the lack of facial response which makes me nervous because I can't read the listeners response and my negativity bias makes me think they must think i'm rambling. Definitely feels like a self fulfilling prophecy.
You've made a solo podcast 21:12 (great album eh), and you definitely sound experienced in monologues.
Monologues definitely take practice. I've had a lot of time to practice :)
I think great communication is learned, it's definitely not something that is blessed upon us, or it wasn't me anyway.