A filter will likely filter more efficiently from 5k-10k miles than it did initially, from 0-5k miles. If the filter is not flow restricted from approaching or exceeding its max capacity (listed in grams, usually) then it is, in fact, filtering more efficiently.
For modern, well-maintained engines, I would argue that oil AND filter are equally important. People just assume filters can’t last as long as they can. No problem with 10k OCI’s, but 10k OFIs!? Are you out of your mind!?
I wonder if more people would be ok running their filters to 10k miles if the OEM said 20k was fine for warranty purposes.