A lot of memes since the start of classic have emphasized how 'easy' classic is. Part of this is because game challenge has improved over years alongside player skill; addons have gotten better; more youtube, data analysis; DPS and HPS simulators. Logging and analysis is a daily routine, the crowdsourced MMO crowd can outwit and outthink a team of 30-50 developers by sheer numbers.
Vanilla was, for the most part, easy. The hardest part was the roster boss and getting optimal class balance in 40 man raids. Naxx 40 was harder than Naxx 25 in Wrath, but it was relatively easy compared to even heroic raid difficulty in retail nowadays.
TBC was a step up in difficulty, but not tremendously so. Magtheridon was hard in 2008, he was a speedbump in 2021. SSC and TK were a step up in difficulty, Kael Thas and particularly Vashj separating the casual raiders from committed players; again not too hard.
Tier 6 was the 2.3+ nerfed versions, and aside from Illidari Council, Illidan, and Archimonde most of the bosses were speedbumps. Easier than T5 raiding for the most part (if you had the gear).
And now...Sunwell. Well, now we're into the meat of classic raiding and it DEFINITELY is harder.
Looking at the logs after 2 weeks, we see a ridiculously small number of guilds actively clearing Sunwell at launch. Only ~11% of attempts on Kalecgos actually succeed, and he's the easiest boss in the instance as a warmup.
https://classic.warcraftlogs.com/zon...ric=fightwipes
(As of May 17th, 2022)
10.8% of Kalec attempts result in a kill.
6.1% of Brutallus
9.8% of Felmyst
6.9% on Twins
If you've survived those filters, you get the opportunity to attempt to kill M'uru. His (it's?) legacy as the guild killer is maintained, with a 2% clear rate for guilds that can make it that far!
Sunwell is the real deal. Bring your mains, make sure you have best in slot, watch every guide and use every addon you can leverage because you'll need it.