Small change compared to fossil fuels.

Climate-change denial is just like tobacco-cancer denial. It's the same banal "I win, you all lose" mechanism. Enormous resources are available (along with the useful idiots) to propagate falsehoods.

You are mistaking the beneficiaries here. Carbon credit scheme is indeed a greenwashing scam and it is pushed by the oil and gas (plus adjacent) industries. It is plainly obvious that shuffling emissions between jurisdictions does jack shit against reducing the actual real amount of emissions to the atmosphere. Basically the main proponents of the carbon credit fraud are the same people financially motivated to reject long term climate change consequences (aka anti-"catastrophists" in your lingo).

If cap-and-trade held the same levels forever you would be correct. But all of the cap-and-trade systems I am aware of have a built-in lowering of the cap over time. So they start out doing nothing/very little, then ramp up to meaningful reductions over time.

The idea being both to make it easy to get people to agree today (the reductions are tomorrow's problem), and to allow time (and foresight) for industry to adapt to where things are going.