For few simple reasons:
They feel like an afterthought in comparison, yet they somehow cost 80 prisms.
If Blizz wants Mythic weapons to sell better, their graphics have to be enabled for everyone, not just the buyer.
You are right though – Mythic weapons are an afterthought and shameless money grab.
Initially I was thinking the same thing and thought that they were choosing to miss out on promotion opportunities by hiding the effect for everyone but the owner and didn’t know why.
Then someone told me that this may have been because when you get multiple mythic weap owners in the same game on both sides then the animations may overwhelm the battlefield as elims happen. That kind of made sense to me. It sucks missing out on seeing them, but I can see too many being a distraction.
This can only happen in game modes where multiple copies of the same character are allowed to be active per team… so it would be an issue in Arcade mode, but all others could easily support having mythic weapon effects enabled. Mythic effects can sell the weapon – if other players could see them 
I agree on that point. I think that having too much VFX on the field is detrimental.
But the point is, they have to do less work in this regard, compared to mythic skins for example, the effects of which are universal.
So, this fits the same “lower effort” narrative, which makes the price unjustifiable.
I don’t know about that, just completing a BP and getting a mythic is kind of dirt cheap.
Unless you’re a collector who “needs” every mythic. Then, that’s your own fault.
All my mythics feel free since doing the BP just happens from playing.
Blizz usually prices mythic weapons at $40 each, while the prisms to buy them are $80 USD. Yeah, sux to be a collector!
Unless i’m misunderstanding, you could technically have Ana, Rein, Reaper (whoops, he isnt here yet), and Soldier on each team, so eight mythic weapon bearers, each with elimination animations. Even if we only had three mythic wearers and eliminations happening on both teams, I could see where it’d get crowded.
Edit - Ashe too, nearly forgot about her.
I’m glad not everyone Ana kills gets hit with a giant sword from the sky. It looks cool on my screen, but it would be distracting if effects were visible from everyone else’s weapon.
I wont lie, I dont have a single mythic. I thought that since I got the battle pass I might end up getting one, but honestly? they are either for characters I don’t play or aren’t appealing…or both
This is a good thing.
What heroes do (including their attacks) should be instantly recognisable.
Having sounds or visuals change can make this difficult, especially for newer players.
I only bought one with prisms I got from the battlepass, and it was for Soldier, who I rarely ever play. The fact that only I can see them and since there isn’t one for supports I play regularly was a big factor in not racing to grab them.
Please no… I really don’t need 9 distracting explosions in the game that have no value other than stroking one’s own ego. If anything, please add an option to disable them.
Mythic weapon effects are controlled via graphics options switch. It is set to OFF by default. I’m proposing to switch it to ON as a standard, but players can always turn if off if it is too annoying.
Not just an arcade issue. Just imagine a mirror match-up with both teams running Rein, Ana, and Soldier. That’s gonna be random explosions all over the screen for either team getting the kills. Then plug in any hero that gets a mythic weapon into the mix… vfx overload.
Having 1 or more mythic weapons per side isn’t a big deal since color variations could be added to differentiate between each side’s elim effects. And as mentioned before, players can always turn these effects off via option switch.
Having the need to turn off visual overload just shows you made a problem.
It’s not a problem for me… I can process the extra graphics
Not sure about others though…
That’s probably why mythic weapon elim effects are disabled by default. I do not see it as a big issue, but others disagree. Either way, no one sees them now other than their owners, and that is fine too.
No use having a conversation on the topic. They have it locked to the player who owns the gun for just that reason. Same as custom vfx for the mythic skins, not adding more confusing distractions to the game than there already is. If you need more visual stimulus to keep you entertained then just have subway surfers playing on your other monitor.