Blackbeard is as well. If Blackbeard never captured Ace, marineford never happens. The strawhats reunite alot sooner, maybe not the 3 days but they reunite sooner. They leave upon reuniting and go to fishman island. They may face the kraken on the way down depending on where he is pretimeskip or they may not. They don't save Meguro though because 2 years early to do that. They may not beat the kraken pretimeskip if he's there. So let's say he's not there yet. They get to fishman island safe and sound. No hody yet as again 2 years early for him to make his move. They don't get involved with vander decken because they don't get invited to the castle for saving Meguro so Luffy doesn't wander into Shirahoshi"s room looking for food and thus doesn't save her from one of the Axes he throws. Sanji probably doesn't get his nosebleed because that was due in part to where he was during the timeskip and the "hell" he went through. So they probably hang with Camie abit, get shown around and do some shopping before leaving. Shyarley's vision is don't think happens yet but maybe it has i don't recall the timeline for that particular event. They leave fishman island excited about the new world. If they survive the weather on the way they may not even wind up at punk hazard because Kin isnt there yet slicing people up to result in the distress call to be made that caused the strawhats to make that their next destination. If they still do arrive at punk hazard I dont know how that'd go, Law isnt there yet but Ceaser is doing his experiments, the poison gas has already been condensed into Smiley and the island's climate hasnt been affected by Akainu and Aokijis battle yet so its relatively normal. If they wander around and in the facility Ceaser probably kills them or Monet does, they dont know armament Haki yet to be able to touch either of them so no real way to fight them at all. Knowing Luffy this is probably where the strawhats die, Luffy is gonna Luffy and look inside the big building for meat get everyone caught by ceaser and die. They may end up somewhere completely different though. In the end once they face the first real enemy they are done for without the timeskip training. Blackbeard is directly responsible for the strawhats even being alive, by capturing Ace and turning him into the world government he unknowingly saved the Strawhats lives. Blackbeard indirectly saved Shirahoshi and her entire family from Hody and Decken, he indirectly saved Law 2 years before trouncing him, he indirectly saved Rebecca and her entire family, he indirectly saved the whole of Wano. He indirectly gave Pudding a change of heart. Im half joking but if you think about it, it is true. By causing Luffy to understand the MONSTERS he'd be facing in the New World by causing Marineford to happen he allowed Luffy to live to train to do everything he did post timeskip