That Was Easy.

@Background Pony #EFC3
They already had a basic backstory set up for him. It would have been simple to make a few short scenes expanding it.

@Background Pony #8E78
Well, look at it this way. If Grogar was the main antagonist of the series finale, it would’ve left people wanting to know more about him afterwards.

@Background Pony #EFC3
One that involves the trio getting a second chance and even better: reforming. One that doesn’t completely destroy Discord’s character and turns him and the heroes into hypocrites and one that doesn’t have such a ridiculous twist. Really, there’s a million possibilities for a vastly better ending.

@Background Pony #EFC3
Could anyone really think of a better ending?

@Background Pony #0F6A
If the Grogar that brought the villains together was real, and he betrayed them before they could betray him, it would’ve been redundant since the “villain betrays henchmen” trope has already happed twice before.

@Background Pony #EFC3
I don’t see how going to a school counts as a second chance when Discord was literally released to get reformed. Everyone pretty much gave up on Cozy after she was revealed to be a villain. As for Tirek, has anyone ever tried talking to him or reforming him in any way during his over thousand year stay in Tartarus? No. Do we know how that conversation went down exactly? No.

@Background Pony #8E78
She got a chance when she was enrolled in the Friendship School. And Tirek had a chance when his brother Scorpan tried to talk him out of stealing the ponies’ magic and taking over Equestria.

@Smitty1991  
When did Cozy get a second chance? She was never given one and Discord never tried reforming Tirek.

@Background Pony #8E78  
Cozy Glow did on multiple occasions. Even Discord tried reforming Tirek at least twice.

@Smitty1991  
Only for Chrysalis and that was from Starlight and even from her it was the bare minimum compared to what she and Discord got. The other two didn’t even get that.

@Background Pony #85A0  
What are you talking about? The Mane Six reached out to them multiple times to give them a chance to change their ways and they refused.

@A Gruntman  
What’s wrong with you?coward.

@Background Pony #C5F6  
Okay, sheep.

They got what they deserved.

@Background Pony #8E78  
It’s discord, while I myself think and prefer to believe that the trio will be in stone forever, and due to discord playing part in the spell also be aware of their surroundings, its still discord and we simply can’t know what will happen a millennia from now.
 
@Background Pony #2272
 
I think its better than killing them like sombra and the storm king, they could have send them to tartarus(which may not be the best idea, going by what happened in the show), banish them to somewhere(again, where? the moon? is it better than turning them to stone?) for some time will not end their arc, even the targeted audience may notice it, they needed to show that its likely the end of their arc, that the villains are done.

@KSLDRDPL  
A fitting end sure, and I’ll admit, this ending still could have worked if it wasn’t for those minor details.  
If it wasn’t for Discord’s stupid comment about being together forever, and their eerie absence in The Last Problem, that’s what really bothers me.
 
Sure, it’s something different, and the show really needed a fresh idea after reforming every single meany pants. But going from reforming every sour soul, to literally condemning them to an eternity of suspended animation is quite the unexpected departure to say the least.

No doubt the Princesses intended Discord to be imprisoned forever too, but we saw how that worked out.

@KSLDRDPL  
Too bad Discord’s following line completely ruined it.

This is honestly the best possible ending the fandom as a whole could have asked for.  
They were not reformed and paid for what they did, yet, if some people wanted them to reform, its still possible since they are not dead and can be freed.
 
It was the best way to end their arc in the series, a very fitting ending if you ask me(their posses while being stoned also says a lot about their personalities).

“Cozy Glow and Chrysalis were both given chances to reform in their season finales and both rejected. All three villains had the chance to reform during the events of frenemies but chose not to. They have been given enough chances and it’s clear that they are all irredeemable and cannot be reformed. Therefore, turning them to stone was the only logical option.”  
Also bullshit

@Background Pony #888D  
Grogar being discord is what screwed up the show forever, but this is almost as bad. The worst part is Discord united several villains and encouraged them to do whatever they did, and now he gets to decide their punishment. Wasn’t this his fault? Why didn’t Discord get turned back to stone?
 
“But we didn’t want some new guy to be teh final boss”  
Then why the fuck did you even bring back Grogar?  
“Because teh bronies kept begging for him and sent us death thweats”  
Explain Discord choosing Legion of Doom’s punishment  
“But we thought he should do it since he wrote the season”  
WTF!?!  
“And after the events of Daring Doubt, the bronies gave us death threats if we reformed the major villains, so the turning to stone thing was a last minute move.”  
Bullshit

this scene  
this scene right here  
is what screwed up the show forever

Kicking someone when they’re down like this isn’t heroic. It’s bad form.
 
It was bad enough the writers turned Discord into a sociopathic puppeteer, but they had to drag down the princesses as well.