The main reason was to prevent termite, fungus and it could last long. This is true with concrete nesting plank for farms, you don't have to worry about termite, wood bugs,mould, flea,etc.
( concrete & wood nesting planks)By its nature the concrete is stronger and when harvesting it doesn't move, not like the wood planks if it is not properly secured by nails it will move. Birds do not like planks that are easily move or not secured properly when they hang on it they would feel insecure.
The cost of setting up concrete nesting planks is not cheap compared to wood planks. Furthermore it needs experienced workers to do the job and it takes longer time to finish the whole construction works as it needs time for drying.
Most of the concrete planks are engraved with lines for easy perching. The only set back is the concrete smell. Normally it is washed before the farms open. This is to make sure the cement smell is gone.
( combined concrete & wood planks that attracted birds to build nest)Normally it would take a longer time for birds to make nests on concrete planks compared to wood planks but for long term the concrete plank would be the choice. This includes easy harvesting as we don't have to worry about the planks move. Thus this makes harvesting fast.
The concreted planks with its cement nature, you don't have to worry about fungus & mould if the humidity is too high in your farm.
To prevent slow nest making wood planks are added to the concrete planks especially as corner boards. This would help new & young birds to make nests.
( pyramid concrete nesting planks in construction)If you are looking at long term to prevent termite, wood bugs, fungus and maintenance free , the concrete planks would be ideal for your farms. Of course this come with a cost. It is more expensive that wood planks due to workmanship.
But your worries of changing the wood planks in future are history.