I'm sorry, but that's actually how the DMCA works. Originally, a host was held liable for any copyright infringing content, the DMCA allows hosts to pass along responsibility, by saying "we're not the ones who are infringing, it's the uploader who's doing stuff", but in return, if the uploader wishes to contest the copyright, the host has to pass the information of the uploader to the claim submitter.
This isn't mangadex throwing scanlators under the bus, this is literally how the law works.
To clarify when a DMCA claim is made, a host must legally choose one of three options
1) Take responsibility of the upload, and contest it in court themselves. This is non-viable for any hosting site, as they would never escape legal hell
2) Take down the content immediately, without contest. This is what youtube most frequently does.
3) Pass responsibility on to the uploader, giving the uploader the chance to decide whether their content is fair use or not, and contest it if it is. In order for this to happen, both the uploader and the claim submitter must have knowledge of each other.