No, this is not the case. The problem is that we're still far away from evidence based medicine.
When evaluating what works and what doesn't, you have to tread very carefully. Sure, most people^Wgeeks know about double blind studies, but that's just the tip of the iceberg. The second edition of Testing Treatments
came out recently (available as a free pdf on the website, although I bought it to support the authors) that explains the problems in an understandable language while not dumbing down the issues. The book comes with the recommendation of well known epidemiologists like Ben Goldacre, of Bad Science.net fame
To talk about the specifics of screening, check out Chapter 4. To recap the main points there, for screening to be worthwhile you have to look at several factors:
- The condition to be screened for has to be important - either because of it's deadliness and/or because it affects a lot of people
- There has to be a detectable early stage of the condition which to screen against
- There exists an effective and acceptable treatment for the condition
- There is a reliable screening test to detect the condition with
The problem with lots of screening is that on the level of the population it can lead to more harm than good overall for a lot of different diseases, because of false positives, because of our psychological makeup that we'd prefer surgery for even harmless varieties of lumps in our bodies, etc. (see detailed examples in the book). In a lot of cases it happened that screening was introduced before the effectiveness of screening was established in a trial, then later trials showed that the screening was ineffective in reducing deaths or harm.
The bottom line is that well designed trials should be conducted and based on the systemic review of those trials it should be decided whether to conduct screening or not, based on whether it's improving health outcomes or not. A lot of trials don't improve outcomes.