Buddy this isn't rocket science. If Dancer does 9000 DPS by himself and gives 1200 DPS to the raid in the form of buffs, dancer is contributing 10200 rDPS to the raid.
If Bard does 10300 DPS by himself and gives 500 DPS to the raid in the form of buffs, bard is contributing 10500 rDPS to the raid.
Everything you're saying about aDPS literally doesn't matter, aDPS is a metric that can't be compared to rDPS because it literally removes damage, aDPS is meant to ignore any gains from single target buffs and that gain isn't applied to anyone (unlike the rDPS metric which redistributes it), it's straight up removed. aDPS is just there so you can compare yourself to other people
of the same job without it being dependent on your singlet target buff partner playing well, by removing it completely.
Now that we established that rDPS is the only metric that matters for this discussion, in the hypothetical numbers I gave above, Bard's 10500 total rDPS would be bigger than Dancer's 10300 total rDPS.
The actual numbers aren't too far off from the hypothetical according to the site
Not only is bard ahead of dancer, bard doesn't depend as much on other people making proper use of their buffs, dancer's rdps will tank if people are dying or playing badly.