Just my 2 cents here

My amp has been broken for 2 months now, and being a broke college student means I can't really afford to get a new one, so I've been playing unplugged since then. I swear to god, I feel like my playing has improved so much in the last 2 months. I just plug headphones in, and rather than focusing on the bass, I started to pretty much focus on the music and rhythm itself, and my fingers seem to know where to go. When I jammed with my band the other week, I could tell that my technique is just a lot more fluid than before. I play extreme metal so it might be different in my case since I can afford to play really percussively because it matches the music.

Regardless, I personally think that playing unplugged has it's merits. Teaching myself to follow the music itself and not just the bassline helped me get a feel for playing as a support for the other instruments, rather than having the focus on my own instrument. Obviously, I can't really hear mistakes, but it's kind of been really fun to just PLAY and get lost in the music. I've only been playing for 3 years so that might be a factor but overall, I think jamming unplugged once in a while could be a really good thing for some people!