Not to be pedantic, but it's not that it's no longer necessary, but no longer allowed.
The point is its now not allowed to give away products expressly for reviews. You can, however, give away products and ask for a review.
The downside is sites like Fakespot will likely now be unable to discern paid reviews as they won't have the disclaimer.
Amazon Promotions and Commercial Solicitations RulesIn order to preserve the integrity of Community content, content and activities consisting of advertising, promotion, or solicitation (whether direct or indirect) is not allowed, including:
-Creating, modifying, or posting content regarding your (or your relative's, close friend's, business associate's, or employer's) products or services.
-Creating, modifying, or posting content regarding your competitors' products or services.
-Creating, modifying, or posting content in exchange for compensation of any kind (including free or discounted products) or on behalf of anyone else.
-Offering compensation or requesting compensation (including free or discounted products) in exchange for creating, modifying, or posting content-Posting advertisements or solicitations, including URLs with referrer tags or affiliate codes