Kettlebells can be appropriate for new lifters who need but don’t have access to a sufficiently light barbell. There are 2 problems with this approach, however. First, kettlebells come in 4 kg increments (8.8 lbs). Eventually you will either run out of kettlebells to deadlift or you will need a smaller increment between one weight and the next. Either way, you are going to need to graduate to a barbell deadlift for longer term lifting. The second problem with kettlebells is that the mechanics of a kettlebell deadlift will be different from the barbell deadlift. The kettlebell deadlift will be more squat-like.