I would venture to say you’ve got something else going on causing the wear on the heel. My guess would be improperly fit boots and your heel is moving around a lot causing the wear.
I started wearing darn toughs 2 years ago and it’s all I wear now. Even the first pairs I bought aren’t thinning at all.
I’m sure darn tough would replace them, so I would do that and then look at why you’re wearing them out in the same spot because I doubt it’s the socks. A good insole like superfeet really helps isolate the heel.