There is some precedent for this kind of honeymoon. It used to be common for English brides of a certain class to bring a sister along on their honeymoons in the 19th/ 20th centuries. Still, that arrangement tended to presume that a woman would maintain a closer relationship with her sisters than with her husband.
Now, I can see how a contemporary honeymoon is less meaningful for newly weds than honeymoons past. After all, people of previous generations had probably never vacationed with their significant others (and may not have even slept with their significant others) before their honeymoons. Now, there is little mystery involved. Most people cohabit for at least a few years before a wedding, so the getting to know your spouse phase is already complete. Not that alone time with one’s spouse on vacation is ever a bad thing. Personally, I see no reason to have a buddymoon in the 21st century. Friends can always be invited on a non-buddymoon vacation or can be visited where they live.