It's about the long term. For hemp, in this case, Let's say 10 tons are captured per year, 1 ton is burned immediately as biomass. 9 tons is converted into goods which have an average duration of 10 years before being discarded, let's assume that they're burned immediately after 10 years, then you can get a net effect of removing 90 tons after the 10 year mark (hitting a steady state because 9 tons extra are being burned every year from that point on). If you can keep that 9 tons out of the atmosphere for 100 years, you remove 900 tons from the atmosphere after a century.

If those goods are discarded in a manner where the carbon isn't immediately re-released, so they're buried or introduced into a bio-system that can consume it and turn the carbon into some other non-gas form, then you can get further gains.