Arguments against (and for) mulch rings

The more I read about planting trees, the more different recommendations I see.

Most of my new trees to not actually have mulch rings.  I am planning to add them to some to keep the weeds down.  But here is an argument against mulch rings:

http://landscapeofmeaning.blogspot.com/2011/01/case-against-mulch-rings.html

Here's a step-by-step planting guide from NCSU.  This one recommends having the top of the root ball level with the soil surface (not slightly--0.5 inch or so--higher as I have seen recommended elsewhere).  In fact, it suggests you could cover the root ball in soil, but less than one inch (that seems to be disasterous with my high clay soil).   It recommends a water retention ring around the tree, covered with 3 inches of mulch.  So, yes, mulch ring, but also water retention ring around it.  And they even have a partly above ground planting method, where the root ball is about 1/3 above regular soil level, but surrounded with topsoil to 5 times the width, and once again mulch above that.  That is recommended for poorly draining soil, but said to be a problem during dry spells.