Those mechanisms do already exist--marine snow, compacted biomass in wetlands, heck, even things like whale falls store carbon for enormously long periods of time.
The buffer duration/cycle period matters significantly. I agree, turning every bit of carbon released into sticks n wildfire zones won't solve the problem, but in the current situation a) buffering will make a difference in the short term, and b) there are natural mechanisms that do sequester carbon on a functionally permanent basis and keeping those functioning or adding to their capacity through ecological restoration is extremely important and doesn't require new technology.
