I learned the opposite lesson and ended up talking like I write.
There is value in prose that carries your literal voice when the audience is _people who know you_. There is negative value in writing prose that requires the audience to _read it in your voice_ in order for it to make sense, avoid offense, or convey intent.
My prose changed first: it became plain spoken, as devoid of contextual subtlety as I could make it. My career benefitted. My spoken interactions followed.
The only thing that bothers me about it is the nagging sense that I've become so fucking boring.