It works well as a metaphor, which is why people might be fooled to think there might be a direct parallelism without understanding the insurmountable differences between both (depression may be very hard to get out of if you're in a downwards spiral, but definitely possible, while entropy is literally an inevitability of the Universe, as far as our understanding of physics goes) which is why I compared it to the popular appropriation of emotional labor, which notices the poetic similarity but is unable to understand the actual differences between both.