I can beat Duke Fishron as soon as I get a Stormbow. It is just as unfair to compare Moon events to EoL than it is to compare everything you can get after the mech-bosses to FIshron drops. If you're good, you can skip things.
Some players would prefer to take the slower progression route and slowly improve their gear instead of jumping in to fight EoL/Fishron.
And do anyone here thinks Fishron is much harder than EoL? Because if not, then it becomes pointless to accuse EoL of being the problem, and if Fishron IS stronger than EoL, then the latter might need a buff.
Regardless, I do think that the amount of options you have post-plantera/golem was designed so you have many ways of obtaining gear to fight the pillars, the problem here is that there is so much gear you can get, you probably won't need to do all the events/bosses, and you will just be fighting them for fun, unless you really need a slower progression, but even then, a lot of weapons are supposed to have the same strenght (Betsy loot, Fishron loot, EoL loot).
True, one can definitely beat Fishron as soon as they get reasonable late Pre-HM mobility (single horseshoe balloon + spectre boots + dash works fairly well for me) and somewhat reliable weapon (which, in fact, can be pre-Hardmode as well! Molten Fury works wonders, although obviously grabbing a repeater is recommended), while Fishron's wares are a lot more beneficial than mechs. Compared to that, EoL is a lot more harsh, requiring you to have at very least decent wing pair, dash and mount, as well as post-Plantera weapon. There should be almost no disagreeing Fishron is an earlier boss to beat than Empress, and it's okay: Fishron opens up earlier (Any point of Hardmode) than the Empress (Post-Plantera)
However, there has to be a reminder: both bosses are practically post-Golem tier; even Fishron is often skipped as too hard until Golem/pillars by regular players. If you can beat them, you can beat anything following up (with sole exception of mechs
WHILE having abysmally low damage output: night time limitation), so they both are kind of shortcuts you can take on but likely won't unless you know exactly what to do.
Now for the moons themselves. They seem to suffer from being both too harsh and too grindy (in fact, OOA seems to also join that definition, but that's a separate can of worms). Most of the time, if you can reliably get to later waves of them, you don't exactly need the gear they provide, as you already have insane damage to clear it in first place. This is a crucial detail that separates them from mentioned bosses: you cannot as effectively play them without "proper" damage output, due to time constraints. As much as I hate throwing that term around, this is a clear example of DPS check. Personally, the only way I was able to unironically utilize their drops is to bang a wall (dying several times from swarming enemies/bosses, spawn-camping grounded bosses) with underpowered character until something of value is obtained (Pumpkin Moon has Spooky Armor and Necromantic Scrolls, Frost Moon is a bit more generous with
Elf Melter, Razorpine, Christmas Sword, Chain Gun, both have higher tier wings although Spooky are easier to obtain)
And there is another thing to consider, even side bosses (let alone side events) aren't that useful since there is a defined streamline progression: Plantera - > Golem - > Cultist - > first pillar of choice.
Everything past Plantera ended up being somehow easier than Plantera itself, so the recipe for the win is to simply ignore the secondary content and go forward to Celestial weapons (well, obviously one can first grab something from Dungeon if it helps).
I can't argue it's a bad quirk since base content should for the most part be easier than extra, but it certainly does gimper the variety at this part of progression, as for the most part it's unnecessarily loading yourself for even easier time on main bosses.
And, for obvious reasons, once you come to Frost Moon with Astral Arcanum, you hardly need that Razorpine or even Blizzard Staff; same stands for other classes.
Basically, either the timed principle of Moon events has to be reviewed (simple examples: you face much less bulky foes (damage stays generally the same or a bit lower) but if you die, it's over; the event is cumulative and happens each night until you opt out), or the rewards have to be massively rebalanced so it is more worthy to come to these with already decent weaponry. Or something else, as long as it makes events have a well-received place in current gameplay.
