Publishers have always been selective, to lesser or greater degrees. That line from Spieler seems like waffle wording to protect them from over-ambitious author expectations. 'We tried to sell it, honestly, but the publishers are not interested.' Well, duh, maybe it's your fault for taking on a writer who wasn't ready?
In truth, new and uncredentialed authors get signed to the big leagues all the time. They're just generally good writers, or they have a story topical and on-trend enough that it may merit the extra editing.
Spieler kind of lost any interest I might have had. I parse that line as basically meaning 'We might take on projects that are not ready or that we do not believe in, and offer excuses when we've wasted our time and the author's.' I'd rather have an agent who tells me, 'This is bollocks and I can't sell it. Go write me something I can sell.'
Reading deeper into the website, I see that Spieler doesn't seem to take on a lot of fiction anyway, so that doubly removes them from my lists.