WebID and Content Negotiation

There's been some spirited debate on content negotiation

My understanding has always been that content negotiation was an optional
implementation detail, that provides for future proofing, at the expense of
more complexity

This is summed up imho really well in kingley's post:

https://lists.w3.org/Archives/Public/public-webid/2022Jan/0111.html

"Also note, as I've indicated in earlier posts, *content-negotiation is
an implementation detail* (client or server) that should never be in any
spec be it WebID, RDF,  or even the fundamentals of Linked Data Principles.

HTML is the dominant content-type on the Web. It also has a broadly
supported "best practice" for RDF deployment using Structured Data
Islands via the <script/> tag [1]."

Could we come to a consensus that content negotiation is optional for
current and future WebID work?

Or if not, why not?