Kettlebells can get you a long way for sure, but are not really suitable for the bigger lifts from disciplines like powerlifting and olympic lifting. The biggest kettlebell I can find online is 92kg, even with one in each hand that's not enough for many. Part of the benefit of plates and barbells is you load them up 20/25kg at a timel, two 92kg kettle bells would be cumbersome to get into position!