You're talking about the 50 rshares reduction?

I don't know the exact amount. I remember it being described as a small vote on a small account. Whatever the number, I know it is significant because until the latest hard fork, people with small accounts did encounter the situation where they weren't permitted to vote because the deduction took the vote to zero (which was changed in the fork, unfortunately being part of the new conditions which led to one of the chain-crashing bugs).

EDIT: I looked this up, it is 50 million rshares, not 50 rshares. It corresponds to an account with about 1 SP making the typical 10 votes per day, an account with about 10 SP making 100 votes per day, etc. Massive splitting down to, say, 0.1% votes by a moderate stake account will destroy the vote power, and if you see someone/bot doing that it indicates not a successful strategy but likely a mistake.

Is there a store of empty accounts somewhere someone is willing to sell in bulk at a large discount?

Funny you should mention that because I have seen a literal web store where these were being sold. I don't know if this still exists, but someone wanting to milk the system can surely find a source of such accounts by asking around. I occasionally get solicited to buy them, although (note to would be solicitors:) I don't have any interest.

There is in fact, currently, limited demand for this specifically because the system is designed to avoid introducing incentives for splitting (although there are still some), and when developers do find such incentives they try to come up with ways to remove them rather than adding more.

You should take a look at the user @eforucom

1. Looking at one particular account often doesn't mean much. The curation return may appear high because of consistently trailing votes, but in fact that return is being shifted from the trailers to the leaders. This may or may not apply in this case but I'm always skeptical about claims about a particular account which don't make a more comprehensive analysis.
2. "While his curation rewards haven't been anything to write home about very recently" I'm really not sure what to make of this. Very recently may be random variation, temporary conditions due to the fork, changing competition, etc. Without a better analysis, there is no there there.

issues raised here is not "mostly wrong"

Your post is mostly wrong in part not only because it is unlikely (or at least not well supported) that anything harmful exists, but because the suggested "fix" introduces account-splitting incentives which is contrary to an important Steem design principle.

If you: a) have better support for the idea that there is a problem worth solving other than the observation of some votes existing which are likely automated and have a nonzero return (this is fully expected and by design), and b) have a proposed solution that doesn't introduce/increase incentives for account splitting then you may be on to something. But right now, you aren't.