No. It should actually limit horizontal reflow width inside element to screen width. That way you can always read a passage of text by using only vertical scrolling.

In other words, a block element's internal flow width should be restricted to screen width, so that a row of inline elements inside that block can never be wider than screen width.

In other words, text columns should flow at screen width.

Just doing what desktop browsers do would squish the text in a very narrow space. Not desirable.

For me, this is the single most important feature in a mobile (phone) browser.