Just a dumb concern of mine...

[Vidu]

Not doing content during the first few days of the release does put you behind a bit, yes. Personally I like to run content blind and during the first 2 or 3 patch-days I have no problem requesting that from my DF-group. After that period I fully accept that I'm late and that if people want to have a smoother run by explaining/spoiling mechanics, they should have that run.
Specially for 8-man-stuff - if you miss out on the first week when everyone is super happy to have new content to get burnt out by you might run into issues later. Not so much with practise parties, but with farming. I recall farming my Zurvan bird - I got my clear quite late and while I had seen many, many farm parties the past 3 or 4 weeks at the point I could join them, most of them were gone and I was stuck with some really, really bad groups.
For stuff like the lighthouse, where you can get a weekly drop you're obviously one week behind on drops if you dont make it during the first week.

...for certain mechanics and seeing how and that people are failing them I'm not sure how running the content multiple times will help, because they are the result of a general lack of awareness...

In regards to the old EX-primals and (savage) raids I dont really share the concern or dont view it as a problem that people have to wait several hours to fill up synched parties.
Let me explain why: I always considered this content that you do with a static of some sorts - maybe not a full one, maybe by switching out people from time to time and picking up the odd random, but a group of like-minded people knowing in essence. That content was never really meant for DF - each time we got a new EX-primal you couldnt queue up for it by yourself (you needed the full group of 8) and they only opend that up later. And for good reasons - killing most of the EX-primals with a group of 8 unexperienced people in 60 minutes is highly unlikely. So why not go the route of pre-forming the group right away? And why not preform the group out of people you already know, trust and can maybe voice-chat with?
Since the days of Titan Ex I have built a LS dedicated to collect people that are intrested in doing EX-primals. Last year some of us did some synched-minimum-ilvl runs of Coil.
My point is: Doing this the "proper way" has always meant to build a network of like minded people for me - and not only clearing the fight synched. So if you want to do this the proper way surrond yourself with people who share the same goal, put them in LS, invite them to your FC, agree on a date and time when you'll all try to clear Ramuh Ex together!
Its not about "luck" to clear those Ex-primals synched - its about putting in the work to create a network that you can fall back on. (...and then about skill - ...or luck - to get the clear)

As to the approach you described, you're going to find "must've cleared" or at least "must've watched a guide/know mechs" for extreme and savage content on release day. That's not a problem with the game, it's just jerk players.

Why does it make someone a jerk if they want to play with people at the same experience/skill-level as them? I admit that I make the odd joke about must-have-cleared parties on release day aswell or frown a little, but at the end of the day thats a totally legit "desire". Someone has been at this content for the past few hours, got quite far, now wants to kill or farm it - why does it make him a jerk that hes looking for people in a similar situation and has no intrest to repeat the first phase with those who just unlocked the trial again?