I think that many of the people who write clearly are successful. But I am not sure there is evidence of the arrow of causality pointing the other way.

One thing to realize for clear communication is that there is:

1. The thing you wanna say

2. The thing you actually say

3. The words that reach the other

4. The thing they think you say there

And if you do nothing about it, all four might be different constantly. People who are bad at communicating are not even aware of that. They think "wanting" to say something is enough — it is not. If you don't give others the context they need to understand what you want to say that one is on you and totally on you.

Too many people shift the burden of decoding their cryptic messages on the receiving side and wonder when other people go all like ???!!?

what about - The thing they wanted you to say. as well as people trying their best to interpret your words in the worst possible way. It is not always your fault if you were missunderstood

Indeed, but that just means the aspect that twists the message is not under your influence. In this case you can consider to:

A) Say it anyways (bystanders might be your audience, or you might want to be one of many voices who tells them this)

B) Provides you already know your will fall on deaf ears, you could use that knowledge to try a creatively different message that could reach them

C) You just don't waste your energy at all

Very good list. 100% agree.

The added realisation to me is that, the order of priority among those 4 points is reversed for the recipient.

I lost count of the number of times I wrote a nuanced, structured answer on stackoverflow, only to get a tldr effect and have a wildly wrong oneliner chosen as the accepted answer.

It has really driven the point across for me that "better" isn't always better; if a good solution will put off people from even reading it, then sometimes giving people a trivial, supercrap solution to use as a starting point and build from there is the way to go.

I have encountered so many successful people who can barely write a coherent sentence without typos and grammatical errors that it almost seems like there is actually a correlation between success and inability to write. But what they do well instead is talk. They talk much with many unfamiliar people, with confidence.

I would call writing one of the most underrated skills overall, not just for successful people. In fact, I'd extrapolate "write" to "communicate" since the same thing applies to the spoken word, not to mention other ways of communicating (except that speaking and writing are probably the most commonly used).

I'm constantly amazed at how bad some relatively smart people are at writing in particular, let alone communication in general. Getting good at writing is hard, and takes lots of practice.

I think the problem of acquiring good writing skills is

1) getting feedback requires commitment for other people 2) It's pretty subjective