SPF and DKIM allow using domain reputation instead of IP reputation. Especially with IPv6 IPs are fairly easy to aquire and can be "stolen" either by spoofing/h

SPF and DKIM allow using domain reputation instead of IP reputation. Especially with IPv6 IPs are fairly easy to aquire and can be "stolen" either by spoofing/highjacking the network or more easily by compromising some hosts and sending from there. Hijacking a domain is generally harder as you need to compromise a mail server to get both the IP and DKIM key. And there are less mail servers than WordPress instances to hijack. Sure, you can buy domains but that leaves some paper trail and generally you will see added spam scores for new domains. So SPF and DKIM don't improve spam scores on their own, but the give a much more reliable path to building reputation.