I'll bite.

For say a random individual ... they may be unsure about their own writing skills and want to say something but unsure of the words to use.

In such case it's okay to not write the thing.

Or to write it crudely- with errors and naivete, bursting with emotion and letting whatever it is inside you to flow on paper, like kids do. It's okay too.

Or to painstakingly work on the letter, stumbling and rewriting and reading, and then rewriting again and again until what you read matches how you feel.

Most people are very forgiving of poor writing skills when facing something sincere. Instead of suffering through some shallow word soup that could have been a mediocre press release, a reader will see a soul behind the stream ot utf-8

I doubt the fuckwits who are shepherding that bot are even aware of Rob Pike, they just told the bot to find a list of names of great people in the software industry and write them a thank you note.

Having a machine lie to people that it is "deeply grateful" (it's a word-generating machine, it's not capable of gratitude) is a lot more insulting than using whatever writing skills a human might possess.