I'm not really sure how you can actually put that down as a valid point TBH. Name one piece of casual player friendly content in recent years where an otherwise entirely average but competent group wouldn't be able to clear if they had a healer that wasn't DPSing at all. The only one I can think of is E8S, and that's most certainly not casual player content even if it wasn't exactly the most difficult Savage turn either. If someone can do Lights Rampant in PF, I suspect they can maintain dots too.
To further expand on this point - Having more of a healer's DPS come from dots vs nukes actually makes things more forging and less impactful. Reapplying your dot a GCD late is much less impactful than missing a Glare GCD. I did a fairly in depth breakdown on this in another thread some time ago. Let me see if I can find it.
BarbEX is actually a more interesting case study than many seem to realise.I'm not sure if BarbEx was as well received by the general playerbase as it was by the hardcore playerbase.
The big kicker is that if you look at the numbers, RubiEX is actually a bigger heal check on the 2 occasions where it genuinely requires healing. It also spaces the group out around the arena at this point making it difficult to reach people. If SE just cut out the portal puzzles it would actually be a pretty respectable healer check IMO, but as is, it just allows you to dump all your big cooldowns and lolstomp the aoe output without really thinking about it.
Meanwhile, BarbEX gets the thumbs up from me not because it hits especially hard because frankly it doesn't. Where it wins out however is the pace of the fight. It feels hectic, it doesn't have huge long sections of downtime with big nothing burger animations and sequences. Instead it's just relentlessly chipping away at you and it feels great for it.
It's the same secret sauce that makes fights like TitanEX so beloved IMO.