u gotta keep in mind modern training relies on extraphysiological amounts of meat and protein intake. I suspect the bloated muscle bellies can act as protein reserves. These water baloon muscles are reported in medical studies to suck nutrients away from tendons and inhibit tendon growth with cellular signalling.
The modern training regimen also often have rediculous amounts of downtime where ur just sore and resting, which is also unrealistic in non industrial society.
another big issue is maladaptive neural entrainment and movement paths. For exaple bench press is notorious for deactivating the scapula.