The reasons for the decline in the number of libel trials are complicated. One of them certainly is the case law which limited damages effectively to GBP250,000. So now the most you can get is GBP250,000, and if you conduct a long libel trial, the costs are in the millions. That's certainly had a deterrent effect.
But there are still libel litigants with deep pockets. There are still some newspapers with deep pockets.
Cases involving the media fight rarely, and they fight rarely partly for cost reasons and partly because people form early views as to the merits.