“I would guess three players at 200 pounds each would be more effective than one…”
There may be guys who are just fat but many of these plus 300 pounders are ridiculously strong to say nothing of being very fast for their size. More than once I’ve seen one such lineman sweep an opposing lineman aside like so much straw that I wonder how the arm could survive such pressure. Most of those guys on an NFL field are exceptional.
I understand they are exceptional, but there are no restrictions on weight. Having a total on field weight limit would require coaches to balance weight, speed, and strength.