This isn't necessarily a question that can be 100% answered it's more of an opinion piece. I recently shifted to a new company and position and I've been learning how they work in their agile process.
I came from a much larger company with a bigger IT focus with years of agile development under their belt.
Recently in one of our retro's the questions of sub-tasks came up. My old organization we always had sub-tasks usually the basic(Dev,QA,Documentation) then we would add some as needed per the story(If it was complex and had a web element and a db2 element or something).
A majority of the developers didn't see the need of having sub-tasks on stories. Their thought is you don't get enough value out of the effort of making them/using them. I've been tasked with coming up with a suggested use for them and what the benefits of using them are, all I really have is my experience and why I think they are good, but I'd like to get the communities idea of when the right time to use them is, or if there is an opinion on if they are dumb or not!