I have to agree with some of the commenters who are saying that the reasons given to support the unboxing suggestion don’t consider the original intent of the card/post-it design pattern.
If you take a look at the material design guidelines as an example, there’s an excellent explanation of when cards are to be used. In short, they are intended to be used for collections of content (usually non-comparative e.g. social media posts) which is composed of different data types, with variable length and interactive actions.
In light of this recommendation, applying this design pattern to google search results seems invalid, given that the results are a collection of comparable, fixed length, static text items with no interactive action buttons.
I think this article should have focused more on when boxing elements is appropriate, and when it isn’t, then discussing overuse of the pattern on the web at the moment, providing examples. I might write an article on the subject along those lines over the next week.
Link to material design guidelines: https://material.google.com/components/cards.html#