I find that if I don’t create my avatar, I don’t hit my markets sweet spot.
If I am selling weight loss products for example, I create an avatar based on characteristics that I can rank for (I am still a seo guy) and groups that are hungry. While the weight loss niche is huge (and some of the people will be motivated to take action a vast majority will not be ready) and I could go broad and target millions of people (also tons of competition), I prefer to target brides to be, who want to lose weight in 6 months or so for their wedding (they are definitely motivated).
If I did my avatar right I know my customers pain points, their likes, if they prefer to learn via ebooks/videos/services. If my niche spends money or if they are freebie seekers.