designers need feedback from non-designers. a designers title doesnt suddenly give them encompassing knowledge over a business and how to treat every part of a project.
Rather than, "do it this way because businessReasons."
Instead, try, "We must not have properly conveyed this aspect of our business, here is the relevant context. Knowing this, how do we solve this design problem?"
If the designer is incapable of translating business requirements into design solutions then perhaps they're not a product/ux designer, maybe just a visual/graphic designer.
"just as long as there's a verification process to ensure that only designers are giving design feedback"
You can't have it both ways.
Yes like every project that gets designed.
Start thinking real world. Feedback comes from everywhere. A website for example can represent every aspect of a company and stakeholders who will view the early phases, either for suggestions or out of team respect will provide feedback. Doesn't mean a designer responds, but sometimes they have to suck it up and change it, even when they don't think it's better.
And stop talking like just because UX is in front of a title gives somebody special power. It doesn't. Work with a few of them and you'll realize it.