The method is not the goal
The goal is not the method
This is why I cringe anytime someone says "I train kettlebells/TRX/insert tool of choice here"
You don't, unless you're involved in a competitive event revolving around that tool (Kettlebell Sport as an example)
What you do is you use that tool to help you attain your training goals.
You don't "do" aerobics, you use movements to stimulate your aerobic energy system
You train you using Kettlebells, using barbells, using aerobic exercise or using CrossFit
The goal is not the method
The method is not the goal
Regards
Dave Hedges