You don't have to stop eating carbs, but not eating carbs has the possibility[1] to save off some gluconeogenesis by subbing fat for muscle while in ketosis, retaining more gains from the bulk.
All of those studies listed in the review you posted are targeting either overweight people or "normal weight", both miles away from the body composition of a bodybuilder.
You can't take that and try to apply the same results to someone who's got their diet, exercise, sleep, daily steps, even salt intake dialed in like a bodybuilder does.
We all accept there will be muscle loss when you diet down. Heck, most natural bodybuilders probably have to drop 10kg before they are ready to go on stage.
Source: I'm on long-term keto for reasons unrelated to weight.
I'm only doing normal keto so I only have cursory knowledge about this sub and know nothing about the science.
TKD/CKD are variations which incorporate controlled carb intake to promote rapid glycogen recovery. Most people aren't training hard enough to need this.
Also note that dipping below some level of body fat is actively harmful to your body.
Most people only compete every few years