Yeah, bananas have teh carbs you need; avocados don't. You probably wouldn't have much energy from 30 avocados.
I don't think the person who writes about "complete protein" knows about amino acids and the body's ability to combine them.
You would have enough protein if you got enough calories. However, in general, you need the minerals and good fats from green leafy vegetables (not every day necessarily - just during the year, a rounded out varied diet).
That's just the name of the site. Some peopel there eat 30 bananas (or more) per day. That doesn't mean that's the only thing you eat. I could say "I ate 5 apples today" but that statement doesn't exclude me eating anything else. Some people there don't eat bananas at all. Others eat 1 and up.
A good program to figure out the nutrition in food is fitday.com but be mindful when using it that the RDAs are for cooked food eaters who only absorb about 20% of the nutrients they eat; that vitamin D would be related to your sun exposure and B12 from a sublingual; and there is no requirement for consumption of salt (you will get sodium from melons, greens, celery, tomatoes, and other fruits and vegetables).