Not that tightly linked. Whilst the Element client does offer Matrix.org as a signup/login as the first page you see, you're also just one single click from signup/login to any of the other servers. Nothing about that page really feels locked or branded to matrix.org.
I don't see how that makes Element responsible for matrix.org content. Thunderbird offers getting an email address via gandi.net in their new account page. Does that mean that Mozilla is suddenly responsible for all emails (like spam) coming out of gandi?
New Vector leadership holding key decision-making positions on both Element and Matrix.org could be seen as a distinguishing factor. It feels subjectively like more entanglement than the Mozilla/Gandi combo.
We’ve very consciously tried to separate The Matrix.org Foundation from Element (previously known as New Vector), despite both Matrix and Element being created by the same leadership (myself, my co-founder Amandine, and the rest of the core Matrix team). To be clear: we started Matrix in 2014 as a pure R&D project, and then created Element (then NV) in 2017 to keep the core team employed to work on it fulltime.
However, the non-profit Foundation (https://matrix.org/foundation) was set up in 2018 with myself and Amandine deliberately in a minority control position (2 of 5 directors, called Guardians) specifically to address this concern - to protect Matrix from Element’s commercial activity, in case we ever went rogue.
As it happens, The Foundation farms out hosting and admin of the matrix.org homeserver to Element (which makes sense, given the Foundation doesn’t have employees and Element was already running the server), but if Element ever went evil, i am very confident that the Foundation Guardians would kick in and make a course correction.
I don't see how that makes Element responsible for matrix.org content. Thunderbird offers getting an email address via gandi.net in their new account page. Does that mean that Mozilla is suddenly responsible for all emails (like spam) coming out of gandi?