Not an expert by any means, but I always heard the glue is just as strong, if not stronger than the wood itself. I’m waiting for a dowel-free glue up to dry as we speak, and I’m curious to see how it turns out. It’ll just be a 3/4” thick shelf, though, so I’m not terribly worried about strength. I might have to go with the extra stability of dowels or dominoes if I were working on a tabletop, though.
That "glue is stronger than wood" saying is mostly true. What is meant by that is that wood glue is a stronger binder than the stuff that binds wood fibers together naturally (lignen). However, under bending stress, the strength of wood glue is far inferior to the strength of wood grain. This is where the "don't glue end grains together" myth comes from. End grain joints are fine, but if you expect them to perform like an unbroken fiber, you'll be dissapointed.