I come from a "classical" background doing Martial Arts and Bodybuilding.
That said, I applaud the "new" fitness scene that is developing (more focus on compound exercises, bodyweight drills, natural movements, new/old equipment like kettlebells, sandbags, TRX straps, etc...)
There is a lot of new developments and insights in sports science and medicine that support a lot of these and a lot of these are plain fun.
That said...
There is an awful lot of bro-science around. Starting with nutrition (Paleo, etc..), via training the "core" (while valid, it is an overdone staple in any marketing for these fads) and ending with the clusterfuck that is CrossFit.
While some people get seriously shredded doing Crossfit (heavy weights and endurance, who woulda thunk it?), I don't want to know how many are left crippled.
A cornerstone of crossfit, moving heavy weights in complex, compound exercises FOR TIME ... just makes my head hurt. Say goodbye to your health and safety.
TL;DR: New exercise and fitness developments can be great, Crossfit is not. It is a disgrace for the fitness movement and even BroScientists are ashamed of it.
::emp::