The importance of idea depends on a definition of genre vs literary. This seems to be ignored here both in the referenced blog and the references within the blog. There is no clear definition(beyond unsupported assumption that idea driven are genre and character driven are literature)of what is genre and what is literary and without that it muddies up the whole argument.
What this means is there is a need to examine what is literary and that might be accomplished by examining Thomas Pynchon's Gravity Rainbow as an example of the literary. The idea there still was fresh at the time; however the writing style allowed for more in-depth examination of the character and the absurdity of the character's life within an absurd situations caused by this. Then let's wander into Samual R. Delany's Dalghren; another fine idea at the time, dealing out in-depth look at the characters in relationship to how this idea or world was affecting them. This is more a marriage of ideas and character and close examination of how the two intersect rather than a preference of one over the other.
What is different with those and mainstream science fiction would be that often the style of writing allowed itself to meander off on threads that delve deeper into character and reaction sometimes detrimental to the character agency and ending up muddying any clear picture of a plot. And yet they still work as a novel, to some extent.
Idea and character can survive the marriage when the author adheres to structure and plot and, in fact, can't so easily be separated(split)and defined into types that have ideas or types that have characters(and be well written).
Now let's get back to the OP, because it seems the reference is specific to magazines, which tend to be short stories and are a much more difficult thing to write sometimes. There is less room to develop character and ideas and it is easy to try to compromise one or the other to get to the point and stay within word counts.
It is not the ideas alone or the characters alone that drive a well written story; however, when a preference is forced, that alone is not enough to determine whether it is genre or literary.
Defining Genre and Literary should include how the writing style uses these elements, how it blends them to creates a voice or tone that sticks to plot and character and idea development; or allows it to wander into deeper examination of one or the other often at the expense of plot and agency.
There is a certain balance that creates a well written story, which is more important than determining whether something is genre or literary. And the reference inside the reference seemed more focused on someones determination of what is a well written story in relationship to specific magazines that are loosely defined as either genre or literary and then precede to forget to explain what a well written story should look like. It is uncertain how that might be a good place to start in defining idea driven as one thing and character driven as another.
New ideas are important, yes; but they pale when peopled with undeveloped characters; however, the upside is that someone will eventually take the poorly written stories new ideas and people them with well developed characters and those ideas will likely not be wasted.