Why? Because I think carbon capture sells the idea that with the right technology we could just continue doing what we are doing. It is the equivalent of an obese person stuffing food in their mouth and telling you fat can always be surgically removed. Yeah sure it can, to some degree, but you do see how that doesn't fix the problem? Do you see how them saying that might in fact be worse than them saying nothing?
So in my mind carbon capture is something that we should work on if we are capable of the realization that the role it will play in fixing the problem is utterly insignificant. If you think it is the solution, carbon capture sells a false hope and prolongs the struggle — and at least where I am from proponents of carbon capture are the people who definitely don't want to reduce their CO2 output.
Pointing at some future technology instead of doing something now is actively harmful. And I am not sure the actual positive effect of such technology would outweigh the negative effect it has as an excuse to justify not doing what is necessary now.