I kind of wonder if this is all a precursor to the loosening of MLS transfer rules. As it stands, they take 33% of transfers fees. Let's say RBNY buy Kaku for $6M, with Huracan keeping 20% of his rights. Then in 3 years RBNY sells him to a team in Portugal for $12M. Huracan would keep $2M, but then MLS also takes a 33% cut of the transfer ($4M). RBNY would have sold a player at double the price they bought him and ended up actually earning virtually zero profit. In this scenario, RBNY are paying a fuck-ton for an unproven player and have zero upside in their investment.
But if there are profits to be made, then it makes perfect sense for RBNY to spend big on young South Americans. Yes, spending $15M on two players is a lot, but Red Bull are rich as fuck. They can afford it in the short-term. If in 3 years they are then able to turn that into, let's say, a $5M profit, then they've pretty much covered the cost of running the team for multiple years just from that alone. Let alone whatever is made from tickets sales/merchandise/TV contracts/playoff success.
Or this rumor is a bunch of bullshit, MLS is still going to eat into transfer fees, Kaku will break his ankle in April, and I have no idea what the fuck I am talking about.
The benefit of spending on DPs is that until you recoup all your acquisition cost money back MLS cannot take a cut of the fee you receive, so they only really need to make their money back to make it worth their while. Downside for Red Bull here is a lot smaller than people realize even with the current rule setup. I think personally after Veron, Red Bull was afraid to put not significant cash on a DP until they had the scouting system fixed to their liking (which makes sense). You don't really need as many scouts when you are signing Henry's but you do for Kaku's etc.