Would you drive in it?

That section of the road is often hazardous for cyclists. Its very rough which makes bike control harder, it often contains loose stones, rubbish, broken glass etc too. When you drive there in a car you will hear those things kick up into your wheelarch, but luckily in a car you're protected with a metal cage around you.

A solid white line marks the edge of the carriageway. It’s not usable road in the theory sense. In a practical sense it’s usually full of gravel and debris and would significantly increase the likelihood of a cyclist losing control and falling.

Actually that's not what the cyclist is supposed to do. They should ride at least half a meter from the verge or in the centre of the lane. Why would you give out advice that directly contravenes the highway code?

No chance. It's limits your safe space even more.