A modern WHM relies on those things, a LV50 WHM running Urth's Font synced does not. That fight was designed well before HW and SB abilities were available, and that fight was cleared long before HW and SB abilities were available. The fight is even easier now with the role skills you are allowed to take, and being over geared.

If you are running out of mana quickly in that fight, it's because damage and KOs are high, or you are not managing your MP properly. I run that fight at least once a week on my WHM and I never have any MP issues unless the afore mentioned are a factor. As such, here a few things I notice in PUGs that make this fight more difficult than it has to be.

The two biggest causes of wipes in this fight are players getting inflicted with terror which severely reduces overall DPS (this is totally avoidable), and not taking care of the bleed mechanic. The latter forces you to heal more than necessary, and will sap your MP dry keeping everyone alive if not taken care of.

You also have another healer there that should be helping out.