Because talking about carbon capture let's emitting companies not do anything to reduce emissions and tell themselves and the public "ah, we're just gonna do carbon capture in the future". It's the same with hydrogen btw., there won't be enough of it for our current use of fossils, we know it, but we still tell ourselves "ah, we'll just switch to green H2 as soon as it's available" instead of working to reduce emissions and implement new processes.