Well, it's not "needed" by definition, this is something you'll need to research and eventually define.
As a general rule, the more users, the most chances you'll have they review your product. This way, if you're selling knickers on a site with a big customer base, these customers will probably interact with a review system (whether it's reviewing or reading the reviews to make a decision). If you're selling satellites or nuclear reactors, quite possibly you won't have any review at all!
The above example is an obvious exaggeration to make a point, which is: "Everything in UX depends on context, nothing exists isolated and no answer applies in 100% of cases"
So, if your product is massive, is better to have some reviews. You can display a "review" tab based on conditional
(if $review >=1 --> display $review; else --> display nothing) if you want. You can use empty reviews to invite people to add their reviews. You can use many techniques to achieve this, which are out of the scope of the question and should be defined by you based on.... testing!. But remember: testing may also show you don't really need it, so be open to that result as well.
Besides the links (and answers on your links you mention) , you might be interested in this article by NNGroup: Ecommerce UX: 3 Design Trends to Follow and 3 to Avoid. You will see their recommendation is, not only to have reviews, but to make them more robust:
The Good: More Robust Reviews
Reviews help users understand more about the quality and use of the
product. Reviews can answer questions or address concerns that users
have about the product, because they’re written from the perspective
of people who needed or wanted, and actually used the product.
Offering reviews is helpful, but sites are increasingly taking reviews
farther by offering additional information about the reviewer or by
better summarizing the reviews.
Many sites are adding details to reviews: relevant details about the
person writing the review, such as gender or age, or particular
product criteria for evaluation, such as sizing or quality. Sites are
recognizing top contributors and letting readers rate the value of the
review. They are summarizing keywords and phrases used in positive and
negative reviews, or even highlighting quotes from useful or
Such additional information, when done well, can help make it easier
for users to get the full benefit of others’ opinions. Reviewer
details let users find reviews that are pertinent to their situation
or use, and review summaries help users wade through large numbers of
reviews to see what common issues or strengths the product has.
Finally, some insight from Shopify: The Top UX Elements to Optimize Your Clients’ Product Page Design (you should read it all or just jump to "Reviews"):
Customer reviews are used in two different ways by users. Firstly they
are used to assess the quality of the product and of your service.
Buyers are looking to be reassured that what you say on the rest of
the page is true.
Secondly, buyers often use reviews to find out about features that
might not be listed on the page.
If we take our shoe example, reviews might be read by users to check
if the sizing of the shoes is accurate —e.g. if a size 5 of this shoe
is larger or smaller than normal. If you are selling a bicycle on your
product page, a review might detail the feel of the saddle. And if
it's a washing machine, a review might highlight just how long the
quick wash takes.
If you can build up a good set of reviews, they will add credibility
to your product page and help sell the product on your behalf.
Finally, it’s important to not hide any negative reviews. If all the
reviews are overly positive it leads users to question their accuracy
and validity. Be sure to offer a link to negative reviews as these
often highlight aspects such as fit, that in the long run might help
reduce returns and refunds — a topic we’ll be discussing in a future
It's NOT NEEDED, but it's BETTER