Some older, unsupported code or whatever, yeah I get that. Apparently changing every last little thing was really needed to do that?....whatever.
I questioned Paul, the site owner, on this as well. The quality of the vBulletin forum software has degraded in recent years in ways the average end user would not notice. More of the backend infrastructure where there were issues. It was unfortunate that vBulletin had to be abandoned, but I understand the reasons why Paul made the choice he did.
There is another theme coming out soon that Paul is working on now. It is a darker theme that some people may like.
-Mike