Got a rejection from an editor who nevertheless said, "I REALLY REALLY love" (her caps) the author's work. I know this editor & trust this is true. It illustrates the need for editors to have both editorial & publishing vision for a book. What does this mean?

Simultaneous to evaluating the material. an editor is wondering:
Is the category selling well?
Will this book stand out?
Will this author stand out?
How have similar books sold?
Can we sell enough copies?
Can I make the case to my team?

Too often -- dare I say the majority of time -- rejections happen for publishing reasons not editorial. Invest time & effort to make a clear & compelling publishing case for your book. (I happen to think this proposal does but you can't win them all.)