Maintaining these systems is a chore and tends to wane with time as the people who intigated them decrease in their activity, get ousted, or otherwise leave. D'Hara was really strong on oaths... way back. They were all recorded and taken quite seriously. It was also mostly an initiative of the clique in charge, and even if the one who took power was mostly part of that same clique, the exodus that resulted from the rebellion turned him into a minority as far as this went, other actors having different priorities than recording oaths and various wiki-writing.
I'd also attribute part of the shift in priorities on player density and world politics. Back in the early days, there were numerous knights per lords as the realm was usually tiny, and foreigners were usually too far to be of much relevance. Intra-realm politics was therefore significantly more important. As borders grew, noble count stagnated, and foreign entities grew as well, it was only natural to shift the attention abroad, instead of at home, and we thus saw the rise of various multi-realm entities (Sanguis Astroism, Veinsormoot, Lurian Empire, etc.). Not only are there more foreigners to come into contact with, not only are those contacts worth more than the ones at home (were turnover is both easy and rare due to the low number of candidacies for any given positions), but the intra-realm relations have also matured as many of the characters there have now lived together for years and have a good idea of what to expect from each other.
Heck, even in the Warders of the Temple, such an oath was required and recently taken by many. I don't even think the ranks were adjusted properly as a result of this. This record-keeping is not really intuitive or fun, and mostly requires someone really motivated and with spare time on their hands, and as such, I predict it will only be rarer as time progresses.