Why Most Reviews Are Not Worth Using to Make a Purchase Decision

According to an article on the e-commerce industry news site eccLab entitled ‘How Many E-commerce Sites and Online Shops Are Actually Operating in Japan?’, 1,891,637 shops are operating.
The article dates from March 24, 2017, but I have not heard of a wave of closures since then, so the number today may have increased and is unlikely to have fallen significantly.
Anyone well versed in copywriting or marketing will know that reviews—customer testimonials—are a tool that resonates strongly with prospective customers.
If you have no reviews, you need to make an effort to collect them (this is also a major challenge for me right now). That applies beyond e-commerce, and all the more so in businesses where excessive competition is normal.
However, after buying something, I have never thought, ‘Those customer testimonials I read were absolutely right. No wonder it has 4.6 stars on Amazon’; each time I bought something I was left feeling vaguely dissatisfied.
Even so, I think I subconsciously use reviews as a reference each time I buy, and the justification switch of ‘The reviews are good, so I feel happy with what I bought and with myself’ does kick in. Still, I wondered why I felt uneasy.
Reviews Are Written Immediately After Purchase
For example, on supplement websites, I often see four-star reviews that say things like, ‘I've only just started taking it, so I don't know whether it works yet.’
People presumably bought it hoping for a result such as ultimately losing weight or becoming healthier, so wouldn't the appropriate time to review it be after using it all up? Or reviews organized around the time immediately after purchase, during use, after finishing it, and whether you want to keep buying it would be very different.
You Don't Know Who Wrote the Review
Some reviews offer rich content such as headshots, ages, photographs, or even videos, but ultimately another person is still another person. If someone buys an expensive information product and says, ‘Meeting so-and-so changed my life,’ it is hard to judge without a much closer look at that reviewer's life.
At a seminar held by a foreign-owned coaching company, on the other hand, they were selling a method costing around one million yen. Customers giving testimonials introduced themselves and explained why they were glad to have made the decision, then answered questions from the instructor and the audience. That makes it easier to judge.
Review Formats Have Not Changed for Years
On e-commerce sites, restaurant sites, and comparison sites alike, reviews basically end with what the customer has written. Of course, some let you compare opposing reviews, as Amazon does, or, like Udemy, allow the provider (instructor) to comment on reviews or customers to respond that a review was helpful.
But they do not dig deeper from the consumer's perspective. I ran an e-commerce site for about two years roughly ten years ago, and things have not changed much even now.
Reviews Are Still Effective
In the end, even after reading all the reviews, customers think ‘Well, it's cheap, so I'll try it,’ ‘It's before the consumption tax goes up,’ or ‘My bonus is coming soon’ and, whatever the price, make an emotional decision. This is one of the most basic principles of marketing, but it leaves me uneasy as a consumer.
And although I am writing all this as if I know better, even I, despite understanding it in theory, probably make emotional decisions as a consumer just like everyone else. That is exactly why reviews will continue to be used as a marketing tool without any fundamental major changes.