your problem is you are looking at events that happened in bfa as if they matter. nothing in wow carries between expansions except the broadest strokes of the story.
bfa's story is: the alliance and horde had one last war, then learned to stop fighting and the horde is good now. only sylvanas is bad.
none of the rest of this matters. blizzard doesnt give a shit and its crazy that you morons still debate this every day of your lives. no one at blizzard cares about the specific grievances of the zandalari trolls or orcs or night elves.
as of shadowlands faction war is literally gone from the game but because you people became so emotionally invested in pretend races in a badly written mmorpg you cant detach yourselves from your roleplaying mindset that the war is unfinished. faction war ended bro. no one cares anymore. what you think thrall jaina anduin and baine come back from this and start fighting again?
no one gives a shit about the sunreavers or teldrassil. those things were just done in the moment to get emotional responses from simpletons and if they are later referred to its only to help push the story along the avenue blizzard wants it to go down. now that blizzard is aiming for faction peace you will never hear about the purge of dalaran again in your lives no matter how much cringeworthy blood elf neo nazi rpers want to "avenge" it.
faction merge is inevitable and has been since bfa began. bfa and shadowlands have been a 2 part lead in to it. every current character is pro peace. including all of the ones left behind on azeroth. tyrande started this expansion standing around with all the horde leaders, only cares about sylvanas, and they edited out the part where she yelled at calia. its widely accepted shes either gonna die or get the vengeance sucked out of her in the shadowlands. you are a moron if you think faction war is coming back. blizzard has meticulously removed or reprogammed every character who was willing to fight it.
anyway obviously the answer to the title is no. they couldnt because the horde has done some wild ass shit that's up there with the worst real world war crimes of history. however they will because blizzard have decided faction merge is coming.
so you had all better suck it up lol. or you can spend the next 3 years of your lives deluding yourselves that lor'themar is gonna fight the alliance or turalyon is a meme light nazi flying in the face of literally every moment of characterization he's been given since his return. even when it happens you can keep on whining that the tauren should never forgive taurajo but blizzard's decision has been made and you are just the regurgitating the leftovers of their bfa marketing push which they have forgotten and abandoned long ago.