>stacking evade with non-stat-related effects is easy as pie.

Plain and simple.  Acrobatics.  Hare Stance.  Disengage.  Miragewalk.  Southern Wind(specifically for its Duration).  Fear.  Evasion, the passive from Rogue.  Light Armor Mastery.  And more.

Evade has always been recognized as something you can't really run on some classes.  Black Knights do not support Evade, whatsoever.  Summoners do not support evade(outside of Skitterscale, but even that's meager.)  

There are other classes that, while they don't have an anti-synergy with evade, they do tend to struggle to use it effectively.  I'll call out Engineer and Arbalest as easy examples.

Let's look at classes that *do* synergize with evade, though.  Ranger.  Ghost.  Verglas.  Spellthief.  Demon Hunter.

One of these things is not like the other, of course.  I'll address the last one first.

Demon Hunter uses Cobra to evade auto attacks, working as a very nice defensive tool.  However, Soldier and DH don't have any evade steroids, so typically DH works towards having a very high baseline Evade....

...But that's not particularly necessary if it's simply paired with a class that synergizes with evade in the more traditional way.  Evade Steroids.  I mentioned a lot of them up above.  It's really easy to stack evade out the wazoo if you want to, even just from a passive standpoint.  You don't need cel to do it.

But, you know.  Cel does pop up in two ways.

1.  Cel makes it 'easier' to stack evade at 2 points per invested stat compared to luck, freeing up more stats for Strength for weapon scaling, or Will for FP, or def/res for simply *better* defenses, or faith for FP and crit evade and Devotion armor, or SAN for racials, or whatever else you're willing to squeeze out.

>The counterargument here is really simple.  Celerity allows you to get other stats, but Luck gets you some of those stats you might be looking for.  That extra hit/crit evade is universally useful if you're looking to skimp, since it means you don't get obliterated as bad by people who crit(like, for real, even small amounts help.  People call 140 crit 'impressive' for a lot of weapons), and it means you encounter Evasion DR less often.  And since the majority of evade stacking is done by buffing in the current meta anyway, evasion synergizing classes allow you to proc evasion against Autohitters and put basic hitters in 50/50 positions anyway already.  I don't think anything above 20 or 30 CEL, tops, would have enough bang for your buck when you think about the 10% phys/mag DR you're giving up when you can already get the benefits of that Cel against opponents that it matters against.

In a sense?  You can say this makes cel a 'good stat' because in some builds that don't want to stack quite as many buffs for one reason or another, 20 or 30 CEL can be a little useful.  But then you can look at all the other stats that people pump up wayyy into diminishing returns and there's clearly a disparity.

2.  Cobra.  Just Cobra.  Cobra is a good enough tool that it justifies making an evade build, and with enough stacked evade it can justify running evade without support.  220 evade is enough to make a lot of autohitters miss you, and with a fear-inflicting weapon you can probably 50/50 your average basic hitter- Or better, even, since Cobra gets you a second chance at dodging those too.

>Here's the issue there.  Cobra isn't enough to stop you from dying.  Experienced players understand how it works and will abuse it without struggling.  Multihit moves.  Evasion ignoring moves.  Moves that work in REALLY janky ways with cobra.  Or even moves that will target you multiple times when they proc Snake Dancer.  And we already know that without Cobra, you need some extensive combos that people don't actually use to get enough benefit out of evasion for the sunk costs of Cel/Luck to get to the levels of evade a build needs w/out buffs.  Stuff like Oracle's Preordinance in combination with IPG, or arguably Boxer's Swaying-  But realistically Swaying sucks, Preordinance is a charge based system and as such is weak in teamfights, and IPG can not only be nulled off but also gets consumed for Verglas attacks.

here's, like, the end all be all with Cel and Evasion.

Do you want to spend 50 points on CEL and 50 points on LUC getting yourself 150 Evade, that someone else can buff themselves up to passively during their turns?
Or do you want to spend 50 points on DEF and on RES, making yourself 50% resistant to physical and magical damage?

Rampaging and Acidity can affect def/res.  But Frozen and Knockdown remove Evade entirely and aren't as hard to access as things like Buster Cannon; and Tangled and other debuffs exist for Evade too.  Evade can let you dodge basic hits entirely.  But the enemy can just autohit you unless they have a gun.  Cobra lets you evade autohits- but experienced players understand perfectly how to get around it, leaving it as detrimental in some matchups.  50% reliable DR that's there for you through thick and thin, or 30% DR that can apply to some, but not all, protection ignoring effects, and is, put bluntly, not reliable.  That's the difference between what you're investing here.