WTF with these huge bulk/cut cycles?

Upfront, I am not even an aspiring amateur bodybuilder, just an old dude that likes to look good at the beach.

That said, what is the mentality, or actual benefit, of gaining a bunch of fat, some muscle, and then trying to eliminate that fat while hoping to hold on to some of the muscle.

Real question, would love to hear from guys and girls achieving a competitive physique. No bro science needed.

My personal experience was being overweight, deciding it was time for a change, changing diet, putting in a shitload of cardio, lost 47lbs, ended up skinny fat. Didn’t like that either. Got smart, added strength training. Over the years I weigh maybe 8lbs more than skinny fat but way way way leaner. And feel pretty confident at the beach. Never had to gain and lose 20lbs to get there. Don’t get it, tell me what I’m missing.