A lot of mixed feelings about them...
But I've learned about writers - just as you very well said.
I am somewhat of a "control freak" when it comes to writing - so the minute I sense my hand or mind are "forced" - I'll run and hide!
A prompt or challenge may "inspire" an idea - and in that regard, I love them...I use them to help me down a thinking or feeling - but to directly answer. I know it won't help me grow as a writer, and so I just don't.
I have done it a couple of times and did it for the fun of it - so hey, the exceptions occur - cause, why not? ;-)
Loved this post! I think you spoke for many of us!
Gracias Gulgo!