IMO, there is nothing really "wrong" with linseed oil.
It does have its weaknesses though.
First off, without dryers added to it, it takes almost forever to dry.
It also is not very waterproof so if a gun is finished with it and raindrops get on the surface they can leave marks.
If the gun is finished with a very plain non shiny surface the spots will be hard to see but if many coats of linseed are used and buffed to a nice shine the spots will be very obvious.
On the plus side, a stock finished to a somewhat dull shine with linseed oil is very easy to fix if it gets scratched or water spotted while some of the harder, faster drying finishes are quite difficult to repair.
It does have its weaknesses though.
First off, without dryers added to it, it takes almost forever to dry.
It also is not very waterproof so if a gun is finished with it and raindrops get on the surface they can leave marks.
If the gun is finished with a very plain non shiny surface the spots will be hard to see but if many coats of linseed are used and buffed to a nice shine the spots will be very obvious.
On the plus side, a stock finished to a somewhat dull shine with linseed oil is very easy to fix if it gets scratched or water spotted while some of the harder, faster drying finishes are quite difficult to repair.