Why browser zoom shouldn’t kill flexible layouts from zomigi talks about whether browser zoom solves all the problems solved by flexible and liquid layouts. Zoe contends that zoom doesn’t do all that.
The fallacy of page zooming from All in the Head is another voice in the discussion.
And two posts from early in the discussion from Authentic Boredom that argue for a return to pixels for font-size: The Debate over Page Zooming and Text Scaling and Coding like its 1999.