Their headphone jacks go kaput so quickly. I'm on my second Rift S (I warrantied thinged the first one) and the headphone bug is starting to happen. At some point within the next year, I'm going to have to go through the process again. I'm biting the bullet right now. But seriously? Why the cheap headphone jacks? Wouldn't it be cheaper to put a good one in so the company doesn't lose money after the warranty?
Sounds like you may be a bit snake-bit there. I know the mic can be iffy and is a known problem for many, have not seen too much of the sound being a problem. I have been using earbuds with my Rift S headphone jack since getting it in Jan 2017 and not had any issue at all. Course I could just be one of the lucky ones.
You also need to remember that most people don't use it. One reason I put my Vive in a box and never used it again after I received my Touch controllers was because using headphones with the Vive was a nightmare compared to the Rift's built-in audio.