This largely misses what an interview is all about, save for entry level positions.

given the in-person interview is at the end of the funnel by a factor of 500-1000, standardized testing might even open up opportunity for under represented candidates.

Think of how poor the screening process is at the recruiter & CTS (left side) of the funnel, and how many false negatives there are .

If you could offer standardized test at that level, you may be able to keep viable candidates in the funnel longer.

I don’t think that the suggestion is that the standarised test is the only filter. It is merely one out of many.