Blockstream does not "basically represent core". That is a common misunderstanding spread by r/btc FUDers.
How so? By comparison of these two pages: https://bitcoincore.org/en/team/ and https://www.blockstream.com/team/ I found that 4 people work for both companies. That's dangerously high and implicating number. And that's what's shown, I believe there are more to know about happening behind the curtains.