Gotta love organic db schemas with long history...
This is horrifying, but at least not as horrifying as the public sector database I once had to work with that predated proper support for foreign keys, so there was a relationship table that was about 4 columns wide and must have had more rows than the rest of the database combined.
Even the database they had moved this schema to struggled with that many join operations.
But parent is right that the choice of what shouldn't be coming from your DBA; they should be more interested in how.
That isn't the end of the conversation; if the response to "we shouldn't do Y" is "it'll be a pain if we can't do Y", then you can explore solution space together, where that solution space includes both trade-offs to support doing Y and alternatives to doing Y. Use experts for their expertise, rather than the equivalent of "I don't care, make it happen".
Or, in short: yes, of course the DBA doesn't unilaterally dictate the architecture, but maybe listen to their expertise anyway.