As with most headlines that end in a question mark, the answer is "No," though in this case the more accurate answer is, "Not entirely but it may be playing a part."
If you've paid any attention to bodybuilding over the years, even just lightly, you may have noticed that the builds have gone from simply being large and well-defined to outright massive, as exemplified by the "super heavyweight" category having a minimum weight of 220 lbs and has competitors as large as 282 lbs…and that's during competition. Bodybuilders tend to weigh more during a "bulking" phase before trimming down to approximately 0% body fat for competition.
So what's with the massive size? In an opinion piece at Slate, Adam Ragusea speculates that meathead machismo and sexual insecurity are the largest contributor to the competition's deviation from a general cultural aesthetic ideal, saying,
It’s all about making straight dudes feel secure watching oiled men flex and pose in tiny skivvies…[I]t’s a lot safer for an unenlightened meathead to idolize another man for his genetic and gym/drug/diet-fueled freakishness than his beauty.
Because this is the world we live in: evidently the only people who can appreciate the male form for aesthetics and beauty are gay men.