I go after the faction, not the players. My knowledge of the fluff is based mainly on what I read in Codices and supplements over roughly 10 years of playing a wide variety of armies in the TTG (including a few variants of Space Marines) and also from reading summaries of various books from people who have read them and are trying to convince me of how good they are, along with excerpts from those books.

Loyalist has a lot of good part of lore (like a LOT) and often they got piece of wtf and they were the only to no care about it being "legit" since it gave a picture of very powerful and manly LSM.

When a space marine (all chapter master he was) find a way to kill a god incarnation, all was normal.
When a chapter found a way to stop a Tendril where a lot tried and failed before them, all was normal. And when I say a lot: Ork, Eldar, Necron, Tau, Imperial Guard, fucking Catachan (those guys are probably the most fit to fight against Tyranids).

Suddenly, Arlequins find a way to penetrate Golden palace's defenses, but get rekt before they could enter the Golden Throne's chamber. LSM lose their mind.

I didn't read all the books, but with those kind of stories, I can safely say that GW's campaign about LSM promotion is still not over.

Have the Eldar not learned to make a virus bomb to wipe out an entire planet of humans?

Well, you're talking production here mostly.

We've been promissed a lot of stuff.
Ranger being most recent and "you'll get it in next 2 months" only to have it changed to completely different thing next week.

Remember how bE promised expansion every 3 months?
When was last time we've got something meaningful that wouldn't be a skin or map?

From community management pov, bE is in really shitty situation right now, promising stuff and not delivering it, delivering dumbed down version of it, or sitting quietly, saying nothing and by that creating "is game dead?" thread posters who actually do have a point.

Too many things were put for later, too many things were cut off completely and too many of that happened post release.

There might be a future for EC, but I can't see it being very bright when it looks like they lost ability to develop anything changing meta game at all, unique ranger to reused assets autarch except without all the goods we were promised when leaders/warlods will come only ensures me in that conviction.

I still enjoy the game, but play maybe 5% of time I have used to and almost completely lost faith in the developer part of the studio, because design part can do nothing without development resources.

Now really how they work

Dark Eldar probably have though, would never use it though

Candidly i'v never gotten the impression you held anything but malice for Space Marine players but hey, tat's just me. Also yes i'd agree the Codex's and supplements are largely bolter porn, they were deliberately made to read like propaganda.

Yes Astartes have a ton of lore compared to other races that's inarguable, but Space Marines are...well...Space Marines, people confuse plot armor with what is just their nature. They do things others can't do, they are supersoldiers, it's their job. I would point out groups like the Blood Angels, Lamenters, Imperial Fists, White Consuls and others have nearly gone extinct at points due to the power of their enemies or sheer misfortune.

Given all the things bE have said that did not come to pass, skepticism and "believing it when you see it" seem like the correct mindset to have when it comes to their claims of what they're going to produce, and especially when they're going to release it.

You've only known me for, what, six months? A year? That's long after my hatred of LSM as a faction started. Also I think you misinterpret my anger toward LSM as a faction for anger toward LSM players, because I tend to express it while talking to LSM players.

Really, just because I'm angry about something while I'm talking, doesn't mean I'm angry at the person I'm talking to.

Since when do any Eldar have any sort of moral or ethical problems with killing humans in any way imaginable?

And they are all great chapters, honestly Space Marines need more shame and defeats in books, being a fan of Imperial Fists and reading about the Iron Cage makes me care for the chapter more and makes you feel hate for the other party, Like in the Ultramarine film, I felt nothing for them as they only lost 1 or 2 dudes in a chaos horde and a captain threw himself of a cliff but me seeing the Fists all die holding ground make them feel more desperate and weak and heroic, constant wins is rather bland to read

Eldar want a galaxy to annex for a future empire, they don't want a Krieg, viral bombs goes against that, for Dark Eldar it's more effective to extract pain from slaves than to get them from a virus bombs, plus it's more "fun"

Terraforming is a thing.

And other races are toddler?

Ork are an endless swarm of big muscular shroom, meaning they can easily do a long war against tyranids.
Eldar have trained soldier too and superior technologies.
Necron are built to kill and can go for a long war against tyranids too as long as biovore don't eat them too much.
Catachan who are still alive trained against primal Tyranid and have already dealt with genestealers and lictors (what the fuck do you the think the Catachan's Evil is?)
Tau got probably killed by tunneling strategies from the Tyranid but they have more firepower than SM.

Space marine? One ship did a uncontrolled warp jump and suddenly the Tendril goes away.
A Dreadnought take down a Demon Prince, no problem...

The SM being just being SM answer is the problem, they will accept any extravagant part of lore (going in SM direction) since someone will say "Muh Space Marine"...