[sokoloff]

This is a particularly bad experience for mobile users with battery and CPU cooling limitations to computing.

While the growth of mobile probably wasn't a primary reason, I suspect the founders may have seen that the future didn't look great, even if they could solve the monetization of exploits and collapse of crypto prices overall headwinds. With crypto pricing falling to near the power input costs when mined on ASICs and GPUs, CPU mining from Javascript was going to be a case where users paid $1 for ~$0.10 of crypto which only a tiny sliver of the original input ($1) went to the content creator.