It's not a situation where anyone is joining the content under the recommended item level,
the content is balanced for higher item level that is available for the players. So if you're joining Savage content as a healer, at
any item level before overgearing/echo, your DPS contribution
will be needed, no matter how good the rest of your party is. Because the DPS checks
are set so high they are impossible to beat without healer DPS, it's also the healers' responsibility. And even if they wouldn't be (which might be the case with at least OS1 and OS2, which seem to be balanced lower than the raids have usually been),
if you're leaving it for your DDs and tanks alone it means you're asking close to optimal maximum performance from them just so you yourself could perform far below the average of your optimal performance.
I do recommend you to check the party DPS required for these fights, then divide it between DDs and tanks alone, then check from logs how good you would ask your DDs and tanks to be to reach those numbers. For example, since OS4 apparently requires 24k party DPS, if your tanks do 6K combined and LBs do 700, it leaves 17,3K DPS for your DDs alone. That is 4325 DPS for each DD.
A PLD doing 3k DPS would currently rank 87%, a WAR 97%, and a DRK 92%. So your tanks would have to be in the top 3-13% of all the players for that job in the whole world.
For DDs, 4325 DPS would mean 98% for BRD, 97% for MCH, 95% for NIN, 94% for RDM, 93% for DRG, 77% for BLM and 75% for SMN. So for any of these jobs, they would have to be in up to the top 2% in their job. Of all the players in the world. (It would only require 56% for MNK and 31% for SAM though!

)
Now tell me with a straight face that it's completely fine to expect that kind of performance level from your DDs and tanks (particularly if you don't happen to have PLD, MNK or SAM in your raid team),
to literally expect them to be some of the very best players in the whole world, all 6 of your other party members, while you and your healing partner would take no responsibility whatsoever for DPS. Please tell me how it would be a reasonable expectation for the tanks and DDs and if they wouldn't somehow happen to succeed to be the world's best and wanted their healers to contibute, they would be "shifting the blame".
