Except that energy usage is mostly zero-sum: if Bitcoin is using all renewable energy sources [0], then all other uses of energy must use dirtier sources if those sources are already heavily utilized by bitcoin. Homes have to use more coal if Bitcoin is using all the wind/hydro. The pool of available energy resources is currently quite finite and while "the grid" abstracts away most of the sources from your view as an electricity user, it doesn't eliminate the fact that there are some very big zero-sum tradeoffs between the sources and "the grid" will adjust to increased demand with increased supply of increasingly dirty sources to meet that demand.

[0] Which is a presumption that is extremely arguable given how much we've seen shutdowns/restarts of coal-powered plants in for instance China and Kazakhstan impact the Bitcoin mining pools over time.