WD40 does no harm to O rings, it doesn’t take much googling to establish this. However it’s also not an especially good lubricant for motorcycle chains, being a very mild solution physically. It’s why WD40 has both dedicated chain cleaner and lubricants to fulfill those roles. Ultimately I suspect there’s little difference in O ring chain life between those who use WD40 regularly, those who use other methods, and those who do pretty well no maintenance, and that riding styles and regular adjustment explain variations.
No, WD40 doesn’t destroy the O rings but it does wash away the lube that the O rings are designed to keep in place.