PSA: I know 7.2 will be released soon. I just want to write down what insanity it would take for a returning player to start raiding mythic and not be a liability for the group right now. Tl/tr at bottom
So let's say you are a retuning player. You are quite skilled and used to raid mythic BRF. For some reason you couldn't/didn't want to start at legion launch but want back in the game now. You want to rejoin your old guild and kick it off with them like old times. But halt! you are not yet Mythic ready!
How long would it take you to be mythic ready? And i mean ready for Krosus and beyond.
You are pretty hardcore and managed to level from 100 to 110 in 2 days. Sweet! Let's run through farm raids for 2 resets and i'm good 2 go! Nope!
First you need to farm 7.5k order hall resources to get lvl 15AK. In addition to that you'll need an additional 1k to get the research running.
Then you need another 2550 for the first few Order hall researches.
You definitely are a liability for a guild progressing on Krosus if you don't have at least 2 legendary items. So over the next 2-3 week you will need to farm another 37500 order hall resources. Oh and don't forget the remaining 4k to keep your Artifact research going.
So we are now at a total of 52550 order hall research you need to farm in about a month. Why a month? because it'll take you a month to get to AK 25.
In order to get that many you'll need to do 3-4 world quests every day for 30 days. Oh, let's forget all the questboards and champion equip. we just wanna get ready to raid.
Let's say in those 30 days you did 10 mythic+ a week. So by the time you reach AK25 you've done 40 runs and have gotten about 3.4 mill AP from that. Let's say you get that same amount again from quests. So now you have a total of 6.8 mill AP. That's enough for 36 traits.
Now I can Raid and not be a burden to my raid, right? Well, not quite. You are still missing 9.5% dmg from your artifact traits. Let's say you need 50 traits to not be a burden. Because let's be real. For a first kill on Krosus every dps needs to pull their weight and because you only got 1 average throughput legendary and 1 utility legendary you are kind of dependent on the traits.
So how much longer will it take to get 50 traits in my weapon? Over 200 maw runs if you get 200k AP per run on average.
Fuck it, let's say you get half of the AP from quests and you nerd it up a bit and do 20 maw runs a week. So after another 5 weeks you are AK 50 and finally ready to go. Fuck yeah!
Let's moon lit this bitch up.. wait a second, you are a Moonkin? Uhm, sorry bro. Even if you preform above average and are in the 75th percentile your DPS is still below the average we need to kill him even if we 3 heal. Sorry but pls sit on the bench for this one.
TL/TR in order for a retuning player to get ready for Mythic raiding you need 9 weeks of hardcore farming. That's an insane hurdle for new/returning players to go through to get ready for raiding and one reason why it is so difficult for guilds to recruit new people.
Sorry for the rant guys I just find that insane of you consider you could get raid ready by running through 2 weeks of farm content after you get to max level in earlier expansions.