10 reviews means the developer has some combination of the following:

• friends/family/classmates
• developers on the actual game
• multiple Steam accounts with the same owner

10 is essentially 0 and cannot be extrapolated into sales.

I agree that if game development is a hobby and not a career, this isn't a problem for those developers.

I also submit that if you are attempting to make money from your efforts and don't yet have a following, and can't afford a marketing budget, and have actually made something unique, interesting, or otherwise worthwhile, it is more difficult to stand out in a market whose signal to noise ratio is continuously and exponentially growing noisier.