"Buying grants to pollute" is literally how cap-and-trade systems work, and they've been extremely effective at reducing pollution. We don't hear about "acid rain" anymore because of cap-and-trade of sulfur dioxide.

But we don't really have cap-and-trade for carbon, so the next best thing is public pressure to be net-zero rather than literally zero.

Agreed. Carbon offsetting always reminds me of this old The Register article: https://www.theregister.com/2008/02/01/bofh_episode_4/

I agree with the second sentence but I don't see how it implies the first. "Leave no trace" is a principle of outdoor recreation, not the fundamental meaning of life, and generating greenhouse gases is often necessary to produce goods and services people enjoy.