I'd always recommend new sellers to not buy or fake reviews. Not just from a moral view point, but also from a business one - if Amazon catch you (which they're quite good at now) that's it, no more selling on Amazon for you.
I totally agree with you that the Amazon review system needs a complete overhaul. I've had fake reviews from competitors damaging my sales, and have seen people get hundreds of reviews in a few hours. The issue is that it's too easy to leave a fake review (you don't even need to buy the product), and too few customers leave a real one. Less than 1%.
While I'm sure there are a lot of shady sellers, a lot of legitimate sellers simply scrape the top reviewers lists and send cold-call emails offering samples/discounts in exchange for reviews.
Amazon reviewers who get discount codes or free samples are required to disclose this information in their review.
When I hit the top 1000 reviewers on Amazon Canada, I started to get offers for review samples, and as my ranking improved, I started getting even more offers, with most of them coming from Chinese vendors.
Unfortunately, many sellers of new products take the easiest way out, and go to Fiverr or a similar service to pump up their product with dozens of fake reviews. A few also use fake reviews to bring down competing products. It's a broken mess that misleads buyers and hurts legitimate vendors.