then Composer nukes the WP core files & the phrase SINGLE POINT OF FAILURE echoes through your stupid head b/c everything is symlinked there
— Lisa Linn Allen (@LisaLinnAllen) December 14, 2015
I guess I would rather find the problems quicker than slower. With the symlinked WordPress core, I found a problem very quickly. Another dev had an old copy of composer.json and ran composer update in her playpen. Composer helpfully removed the copy of core that everything was symlinked to and updated WordPress directly in her playpen, I think. Something happened, WordPress was gone, everything was, as we say, hosed.