We use all that because natural gas is cheap. If hydrogen were cheaper than natural gas, we'd use that instead, at least for the industrial processes, and we'd switch away from combustion of a gas in the distributed residential/commercial applications.
Kidding aside: That's the whole point. This is a project that can work without retooling infra all over the world. It's a drop-in replacement to get to carbon-neutral fuel.
This solves problems right now, with limited investment. This isn't about perfection. This is specifically about "works right now, cheap, no impact on the surrounding infrastructure".
(Also, strong doubts on "we'd use hydrogen instead", because storage is a beast. Until that's solved, there is no chance we'd use that)
I don't believe their cost figures (look above; their 250/t for CO2 doesn't jibe), and I think electrification of most residential/commercial uses will be the superior solution (it's more efficient even if the electricity is produced by burning natural gas). Industrially, hydrogen is just fine. After all, industry already manipulates vast quantities of hydrogen.
The fossil fuel uses that are the most difficult to displace involve liquid fuels for transportation; natural gas has limited use there.
