Throughout the history of fitness and exercise there has been many trends and gadgets that make different claims. They usually claim they are the best thing since sliced bread, but the test of time kind of weeds these things out. An example is Indian clubs. Most people don’t even know what these are. Popular in the 19th century up to around 1930’s, they kind of look like bowling pins. They
have many uses, especially in swinging, but they eventually took a
backseat to organized sports that were beginning to be popular. Were these effective? Absolutely. Were they a “cure all”? Definitely not. Indian clubs are just tools.
Everyone knows that you need more than one tool in a toolbox. You can’t rebuild a carburetor with a hammer and you can’t drive a nail wrench. When some new thing is presented in the fitness industry, everyone goes crazy. More
recent examples are suspension trainers, stability balls (Swiss or
BOSU), strongman training, high intensity interval training (HIIT),
kettlebells (a resurgence), bands, yoga, and pilates. The problem is that we think that one thing can do everything. I know people that will only train with kettlebells or just do exercises while standing on a BOSU ball. This makes no sense. This is even true with traditional exercises (barbells, dumbells, and cable machines). Imagine if you saw a trainer working with a client using just a barbell every week for years. Though the barbell is very versatile, it is not always optimal. It’s hard to do a vertical pulling exercise (i.e. chin-up) with a barbell. That is why you need other training tools. Even certain exercises are tools. It does not make any sense for a bodybuilder to do only Olympic lifts. How about sets and reps? Sometimes you see people in CrossFit videos doing fifty power cleans. Obviously power movements are not meant for HIIT.
There are all kinds of examples I could go on discussing. The main point is to be careful with the “cure all” things that promise you an end to all your training problems. Look out for those trainers as well. There is a lot of them.