We are committed to making all content available to all users. All we're doing in the definition of text element is defining attributes of understandability. That's why they are substitutable. The UA needs to allow the user to pick the one that's best for them. They must provide alternatives, the UA's job is not to pick and choose, but export that job to the user.
Profiles help the user make choices.
1.0 Checkpoint 2.3 is about those choices. An equivalent and its equivalency target are peers for each other. The definition of peer doesn't involve users. It says nothing about the disability status of users receiving the content. In our document, we clearly have a requirement in 2.3 to choose.