This is true, but the renewable energy that was used to mine could have supplied the grid to reduce reliance on non-renewables.

If the renewable generation capacity was built entirely for the purpose of crypto mining and in other words, wouldn't have ever been built without it, you could argue that it's zero emissions (or more accurately, some miners are running effectively with zero emissions while others aren't).

However, since the supplies of renewable energy equipment are not unlimited, demand is already high (so you can't argue that you're driving innovation in the sector), and the production of said equipment is very much carbon positive (from mining to processing to transport), it's just not a very strong argument. If anything, mining with renewables reduces further investment in renewables for the grid as it drives equipment prices up, while still indirectly polluting the environment.

No matter how your slice it, terawatt hours of electricity are being used each year to run the networks, when the biggest problem we face as humans is a shortage of energy.

And I say all of this as someone who supports decentralized digital currency. We have a problem in our society where we obscure and mangle the narrative when something we dislike is true.

We should stop lying about what makes us uncomfortable and start focusing on the solutions to the problems. And there are plenty of reasonable options here:

1. Use the excess heat generated from mining to generate more electricity (with considerable efficiency loss) to supply the grid or to put back into the operation, or run any useful chemical process that requires heat.

2. Use the excess heat generated from mining to heat homes, buildings, etc.

3. Move to a more power efficient method of mining such as a PoS instead PoW. Or an entirely new method that hasn't been thought of yet.(Which, IMO, is the only way to prevent centralization once Quantum Computing or Fusion become commercially available).