Not to beat a dead horse with this, but in my opinion it is easy to forget that using a tool to see something closer boils down to this simple, sad an ugly truth. Let me give you a silly example.
Say we make a "binoculars duel" (spaghetti western music here; Sergio Leone, cha-chan).
You choose your weapon among the best "alpha", 8x42 NL, SF, NV, you name it, your 3000 $ alpha that has all the bells and whistles.
I take my lousy, squeaking, plasticky 500 € Canon IS 8x20.
We stand in a line and agree to focus on that far away bird/object and, just like in a western movie, we "draw" our weapons and point to the said bird/object in order to see what it is. Simple as this: with the 8x20 I will be able to see things you can't with a 3000 $ alpha.
Then if we go selecting birds that are further and further way, there will be a moment when you will be unable to tell... but the 8x20 IS will show the detail.
It is a sad and ugly truth (it's "ugly" in part because the image will be ugly compared to the lovely image of the alpha 😁).
And, not only that; continuing with the duel example. Given that IS takes away the shaking/tremor, magnification doesn't count like if comparing non-IS, so that I could actually use a 12x IS, heck, I could even singlehandle a 12x (pretty useless with non-IS) while holding my bourbon on the other hand... and yet see way more detail than with any non IS 8x, 10x, let alone 12x.
Well, that was a bit of a joke (and you know that in every joke there's a grain of joke), but seriously, what I was trying to convey before is just that. Like
@Maljunulo said, every optics has a set of compromises (size, weight, price, etc.) and IS binoculars incorporate an ennnnnormous set of compromises (terrible ergonomics, need for batteries, bulk, etc.). I understand they're a pretty big pill to swallow. However, as in the above mentioned duel, if my life depended on identifying a bird at a single glance... I would never, ever, ever take an alpha, instead I'll grab a lousy 500 € plastic appliance made in Taiwan, because it simply fulfills better the ultimate goal of binoculars: it shows me more, it is able to bring closer what is far away in a way no alpha can.
As I said, using IS has made me re-think optics. What do I want when I see something far away on a branch, or hidden in a bush, or among the clouds? I want to look at it closer, and IS do just that better than non-IS, be it alpha, beta, delta, gamma or omega. The ugly truth is that many IS (I've never tried the Canon 10x42 L ) do it in a pretty poor way in terms of image quality, but they do it.
I remember an old debate between effective vs efficient. Top of the range binoculars are refined to an incredible extent, they're efficient in what they do. But IS binoculars are effective: they do "what" needs to be done better than any other binoculars (always talking about handheld, which is how the majority use their "birding" binoculars, say 8x42, 8x32, 10x42, etc.). But then there's the "how". Well, my Canon IS III 12x36 show worrying amounts of CA, the image is soft, they have the ergonomics of a potato... but they will eat an NL for breakfast and an SF for supper when it comes to ID a bird and appreciating detail. And if they're still hungry, they'll have a NV for desert.
That's why I said that IS somehow break the rules of what we've been used to talk about. We could discuss if CA is better controlled in the NL or SF, we could discuss if the FOV of the NL is better corrected, if the image through a Noctivid is crystalline... and in the meantime, like the tortoise of the tale, the IS will show more detail than any of those.
I'm not saying IS is better or worse, just saying that it incorporates something different (with an ennnnormous set of drawbacks), and if we are talking about why the top of the range binoculars are so good as they are, it could be interesting to acknowledge that there are way cheaper binoculars offering superior performance in probably the most important area: showing your more.
(By the way, whenever I've been using my Canon IS 12x36 intensively for a few weeks and I grab my 8x32 EL SV is like my eyes are going to a spa
So, not to be taken too seriously, just sparkling conversation).