Feline Fanatic you said the placemats were quilted sparsely. Perhaps they were quilted less densely than the batting company recommended?
The distance between quilting is to keep the batting from lumping and shifting. Quilting itself is to hold the three layers of a quilt together and keep the batting from lumping. I don't understand saying any of this affects the lasting quality of the quilt overall. If seams come apart that's due to poor stitching or fabric quality(fraying). If fabric wears out too soon that's due to poor quality fabric.
Of course, you don't have to quilt 10" across just because the batting says you can. The quilting design will decide what looks good on the quilt.
I agree with bkay that the OP comes across as The Quilt Police(tongue in cheek or not) when statements are made disparaging what batting manufacturers put on their packaging as advise as to how to use their product. Re-reading the OP I'm thinking Ellen 1 meant well in her advise. The beginning sounds like she is bashing the manufacturing for giving out bad advise when I think she meant to say quilters should look at the different aspects of the quilting process to decide how to finish their quilt.
I am one of the ones that likes quilting more sparsely. But I look first at what works the best for the design of quilt I'm working on. Sometimes quilting 2-4" apart is problematical to work into the design of the quilt. I find that frustrating but do my best to work with the batting as my biggest concern is the lumping issue.
Just my two cents to say there are others out here that feel(at least in the initial reading of OP) as bkay does.
"Rules" are guidelines to head you in the right direction. There is nothing to say you can't adapt the "rules" to fit your situation.
It really comes down to "it's your quilt, do as you want". You will find in time if what you do works or not.