The problem is that GW2 is a really fast-paced game so 99% of the time people don't realise what you did that took skill.
In PvP they only know you beat them, they probably didn't notice that you blinked backwards flipped your toon in a 180 used a backwards teleporting skill and then stepped back to them with a weaponswap thrown in the mix.
People don't even realise when confusion kills them which is clearly telling something.
If you've ever seen Reckfull play wow you realise that he takes a slow game and plays it fast, he uses skills that don't trigger a GCD to teleport all over the map which you notice but don't realise how he does it, similar things don't really exist in GW2 because speeding up the already fast game makes it "invisible" add a crappy combat log and it's become nigh impossible.
In PvE there's a myriad of reasons why this won't show. The first is that there isn't really a situation where it's needed, the second is again the speed of the game and the third would be the ignorance of the player base.
1. The most skillful thing you do can probably also be done by dodging correctly. An example for me personally would be a dungeon (HotW) where I interrupted trash that does a nasty spike using my mace (OH ofc), only one person of the full group with whom I run dungeons with regularly (I consider them better than average) noticed. But we all could've dodged the attack too.
2. The (optimised) dps ranger relies heavily on not using the dodge button ever, luckily there are two skills built into the sword that have evades. The problem is that one of those's evade is 1/3 as long as a normal dodge meaning your timing has to be spot on to be successful but because of how fast the attacks go people don't really notice.
3. People have issues noticing things like protection on bosses, red circles of doom,... as is the last thing they'll notice is your toon.
The funny thing is that the two classes with the highest skillcap also have the lowest base skill requirement: warrior and ranger.
Warriors are the only class that require weapon-swaps to maximise DPS, on top of this there are a lot of tricks which increase your DPS some examples:
Learn the correct rotations (it involves dodging!), learn to make attacks that can double strike always double strike, wwa weapon-swap cancel, GS auto attack final hit cancel, using wwa instead of dodge.
Rangers require expert timing to ensure you never dodge but use skill evades. Other difficulties are pet micro, positioning (flanking), combo field control and dealing with idiots (you need everyone in your party to melee or you, your pet and your spirit are absolutely worthless.
Why not the other classes?
Guard: only difficulty is knowing what fight requires what utilities (I wish I was kidding)
Mes: pop tw, use feedback/null field, spam auto evade burst nothing hard
Engi: spam bombs or nades, yes that's it
Nec: 2options either stay dagger 100% and auto attack or complicate things and use dagger + axe deathshroud spam, requires being able to read a healthbar!
Thief: use stealth and backstab or if the boss is low heartseeker (keep an eye on stealth cd and ini regen (in the future)
Ele: 2options: staff fire attunement spam lavafont (I'm not kidding) or LH build where you first stack might (requiring a whopping 2 attunement swaps) and then auto attacking. Both options require you to learn the FGS trick for whenever it's off CD but it's simple.