Yeah!! I can as well, it only takes the end of the first pull (maybe even during the first pull) to tell how good the other 3 members are. If it is slow I start looking exactly the reason is. Is the DRG keeping heavy thrust on? Is the MNK keeping GL3 on? is the mnk consistently high tp? does the mnk have enmityon different monsters? (I seen a pure single target mnk and I called out on it since I noticed him tanking one monster while having no hate on everything else) is the BLm casting fire II/flare? thunder? Is the 1092132219832981981 bad brd spamming wide volley, is the brd full mp? ... there is lots of clues you can see, you just think people can't know because your awareness is weak along with your observation skills and innate clock (things taking longer then normal what is going on?)
You want an example that people do this?:
https://youtu.be/eC8PuW58I-M?t=104
She selected herself on purpose to see if people where doing enough damage to the collar (and they weren't, making the SMN doing all the work) It is important to know what is going on and who may be a weak link so if a wipe happens you can coach them. (if that collar is not destroyed fast enough the healer dies)
You just watched a video on why this is WRONG!, it is EASY to see the fight is slow because of bad tank and mnk FFS has nothing to do with healer dps.
Stop throwing around stawmans, You said large downtime is a myth, admitting that is wrong now?