I'm obviously not talking about genuinely fraudulent claims just the ones where none exists and are done to cause honest people problems.
Apparently over 90% (trying to remember where i got that info from)of calls to the fraud hotline are not genuine something I can well believe given that when I worked for the dwp the vast majority of the reports we got were quite obviously malicious that resulted in findings of no fraud and many other area depts reported the same thing.
The other steps we take to combat fraud such as data matching are really very effective, investigating these claims costs money both for the dwp/hmrc and for the claimant and can be very upsetting.
Obviously reports should still be semi anonymously made just only anon with regards to the claimant getting the info.
Personally I couldn't do that to someone even if I had fallen out with them but lots of people do.