Having a battle that you feel you can win, and slowly losing out to an obviously more talented player, who you can see is winning not by some asinine bullshit that you can't do anything about, but who simply uses their tools better than you, and achieves success through their own talent and knowledge-- that can be a wonderful experience. A chance to learn, a chance to see that there are still new heights for you to strive for, better ways to play, more options to consider, etc and enjoyable competition where you can appreciate the efforts you made against them, even despite your ultimate lack of success. Rather than feeling like your efforts were negated, and that there was literally nothing you could do against it, because the game doesn't let you have any options, and they can kill you no matter what you build, or what you do-- you feel like you did your best, and have now an idea of another way to try that fight in light of how they beat you last time.
Say an Illaoi kills you, it's entirely because you fucked up and let her be able to kill you. You have counter play and outplay potential for each and every skill she has, and at no point in time are you ever helpless against her, or unable to escape, or unable to outplay. A lot of it is simply being aware of terrain, and especially her tentacles along the walls, and side stepping slow moving, 1 second delayed slams from those tentacles. But notice, there is a delay, and it is up to you to move out of it in the 1 second you are given. Similarly, her Q, the slams from her W and her R, those are all the same slam, and can be counter-played similarly. If she Q's, she casts a slam that starts slightly in front of her, not corresponding to any previous tentacle, but rather her own body. If she lands a W, all tentacles in range will slam towards the target's position when she landed the W. If she ults it does minor PBAoE damage, but then summons 1 tentacle per spirit/champion hit, up to a max of 5. These then hit twice as fast, but are limited to a small circle, and can be avoided entirely by just leaving the circle and backing off.
I've already mentioned things you can obviously see about her slams which lead you to intuitive counterplay that all champions are capable of, but what about the rest of her kit? So, say you died to her E -> R -> W -> W you while you get swatted in her ult circle. She's just hit you and your spirit with a minimum of 2 tentacles 3 times within about 4-4.5 seconds, ~4.5 slams yourself (two tentacles hitting the same target is 1.5x damage x3 = 4.5 do note, if there was another tentacle, or two, or three near by, the damage would instead be 1.75, 2, 2.25 as the damage per tentacle when three hit is 1 + 5 + .25 x slam damage, or 1.75, with every subsequent tentacle continuing to add only 25% of the slam's base damage) with your spirit taking a similar amount, in about 4-4.5 seconds of damage or for simplicity's sake, a slam's worth of damage a second to you and your spirit.
Damage ≈ 1 slam/sec (You + Spirit) --over 4.5 seconds
Her E damage conversion at max rank is "45% (+ 8% per 100 AD)" at level 9 she has a base 101 AD, which gives us 54% damage conversion, so this then becomes:
Damage ≈ 1 slam/sec (You + .54You) --over 4.5 seconds ≈ 1.54 slams/sec (You) for 4.5 seconds = 6.93 ≈ 7 slams worth of damage dealt to you
If you notice from this simplified expression of roughly the information above, if you can avoid getting your spirit taken, an entire term disappears. You might think to yourself, "how much less damage would I have taken if I could have just avoided that bloody E?" But it isn't just 54/154th's of the damage above. . .
What you cannot see but is also important to be aware of, is the fact that there are only three slams to begin with because when she ults they will automatically slam towards any vessels or spirits, and so they would slam immediately at your spirit before her first W. So not only would a term cancel, but the formula loses 1.5 slams so instead of 4.5 slams/4.5 seconds, it now becomes:
Damage ≈ 3 slams / 4.5 seconds (You) = 2/3 slams/sec (You) --over 4.5 seconds = 9/3 = 3 slams worth of damage dealt to you
In actuality, 3.93 ≈ 4 slams worth of damage, or 56.7% of the initial damage is removed simply by not letting her pull your spirit. Dying, and then going into death recap and starting to see this (or just mathing it out afterwards as I like to do; loading the replay and working backwards from any sort of "bullshit" death to try to figure out what happened and how, and what conditioned lead up to it, then the math of what went on) gives you a wonderful "Aha! That's what I can/should/need to do, just hit/avoid X ability/zone/combo/etc and I'll get her/him/it/etc next time!"
Yes, getting killed by Illaoi might at first feel somewhat bad, but when you think about it, you had to have misplayed, and she gives you a chance to see that, and goals to improve towards, and shows you herself how you can avoid that the next time, so it feels like you're improving against her. You're fighting a longer term battle that you're actually winning, even if you just died, and that can feel amazing.