The article lists multiple related to how routing works. While great in concept it is nearly impossible in non residential spaces

There are some incentive misalignments. Each AS that configures it is doing it to protect its neighbors, and does not benefit from itself having configured this way. Best practice suggestions only go so far.

Another aspect is, if you configure it not just with your own prefixes but also that of your peers and downstreams (and their downstreams etc), then you need a source of ground truth. (Remember that not all ASes need to announce everything they have, all the time.) This is usually an out of band database. Then you have the problem of database needing to verify the truth, and keeping all the data fresh, etc.

My read was that networks where traffic originates can and should prevent spoofing (edit: that is, prevent their own networks from sending spoofed traffic, not prevent others from spoofing their addresses) via egress filtering (per BCP38), whereas the stuff about FooCorp and CloudFlare is about transit/destination networks trying to prevent spoofing via ingress filtering. Did I misunderstand something?