I read through almost all of your post and I am impressed with your research as well as piqued as to why you did it. However, it is a valid concern. Let's just say that some people, especially those who have gender identity issues, often wear masks, and what are accounts but masks. But ultimately, they did the work that led to them being able to put multiple masks on and make use of them to cross promote each other. It is also why you have pretty much, in my mind, proven conclusively that these identities are one and the same.
Whether you can say it is a scam, or not, is hard to say exactly. In some respects, such theatre qualifies as valid work towards the rewards gained.
To answer why I have presented this information:
The questions about the accounts already identified and that will be identified have been unanswered for weeks. Any attempt to get answers from those creating and upvoting these accounts - some of which are in fact sock puppets, admittedly - has been met with personal attacks, inflammatory accusations, threats of punishment, and actual heavy flagging from the very people involved with these accounts and their friends. At some point, asking for these people to help resolve the issue became futile. They are not interested in that, for (to me) obvious reasons.
I want other users to have the same information that I have and I want them to be able to make informed decisions about their investments and how they use their influence on Steemit. This particular post has already proven what I had set out to prove - a sock puppet, created by a whale, was being collusively upvoted by that whale and his friends. Regardless of why it was occurring, it was in fact occurring. Unfortunately, it is not limited to this one account. There are others tied to this same whale and his friends.
As to whether or not this is a "scam" -
There's certainly nothing "in the code" that prevents this from happening, but that doesn't necessarily make it socially acceptable. Sock puppetry is generally frowned upon in social media. It's not the same as simply using a pseudonym for writing, especially in this system where readers/curators are using their invested influence to give rewards. Deception in this regard could certainly be considered a scam, particularly when it's perpetrated by those with the power to dole out a large portion of the daily rewards pool - and particularly when they knowingly support the sock that they created. When multiple whales are involved with multiple accounts, it can certainly - at the very least - appear to be a scam and may influence the decisions of potential investors, whether they believe that they can also do the same with their own investments or whether they decide to avoid the platfofm altogether. Neither are good for the overall health of Steem and the Steemit community.
I hope this adequately addressed your inquiry.