It's true that a lot of vegetarian/vegan sources of complete protein can come with "unwanted" calories from carbs or fat, but as I've said before, there have been plenty of competitive bodybuilders that go through contest prep on a vegetarian and/or vegan diet, so it's definitely possible.
I'd use a carb cycling-type of approach, which would obviously allow for some higher carb days. On the few lower carb days, you could incorporate some hemp, rice, or pea protein powder in addition to other protein-rich foods to boost protein intake.
Unprocessed soy whole foods are no problem at all when eaten in moderation like other foods. Like with other foods, the more processed it gets, the more negative issues can accumulate. Berardi actually wrote a great article about this, long before his vegetarian experiment.
He tracked his measurements, posted in the pic above. The right column is the total change over the course of the month. He lost a fraction of an inch on his arms and gained nothing in the waist. His hip measurements increased almost an inch, along with his entire lower body.
I don't know if I'd exactly call that a shitty way to build muscle. He still did put on 7 pounds in a month, the majority of which was muscle.
And most important to remember, it was an experiment. He was trying to bulk up for the month, and he did, but he learned as he went along (like he talked about his allergic reaction to lectins). When I did my two month stint, I was just trying to maintain my bodyweight, but I ended up losing 12 pounds in 8 weeks while still gaining strength in the gym, and I had several people say I was looking leaner.
In any case, dudes who want a meat-free diet will go for it and hopefully do it the smart way. Dudes who want to eat meat, most certainly can and will. Arguing about which way is "best" is wasted energy, just like bodybuilders arguing with powerlifters about biceps training.