And that's fine because that's exactly what SPF/DKIM were designed to do. The spam folder is not a dump of true positives. It's the bucket where you train the filter by evaluating somewhat likely false positives.
A perfect technical configuration doesn't make you inherently trustworthy or provide you with faultless reputation.
Users' interests are served by being informed when this happens. And plain text correspondence is not easily mistaken for malware.
> A perfect technical configuration doesn't make you inherently trustworthy or provide you with faultless reputation.
No one claimed such.
That's exactly what it should be. If somebody sends me an email, it should arrive somewhere that I can see. If that means needing tiers of spam folders, each one spammier than the last, then so be it.