I'm really baffled as to how people still don't realize that finding the OP is key to defeating the WG/Imu afterwards.
Roger literally said that they were too early while standing in front of the OP (sth both Rayleigh and Oden re-emphasized).
WB also said that the world will get turned upside down once the OP is found.
It doesn't get much clearer than that.
They reach Laugh Tale and find the OP first, after that the WG/Imu will get defeated.
Is that guaranteed that it should be only via a battle after finding One Piece?
What are they going to learn exactly?
Some people tricked some people, some people back stabbed some people hundreds of years ago, so this piss Luffy off so much he decides to destroy the government? I doubt.
It should be more than simple history on Laugh Tale.
I've seen a theory that Oda possibly took a lot of notes from another series which has many resembles with the world government, once they could enter that certain location that they shouldn't enter, they can reset everything about the whole verse via a special mechanism.
If Laugh Tale has a mechanism like that it also makes sense why the government can not let anyone find it. Not only they don't want pirates to find it, they don't use their resources to send people to find it. If it was a mere history only, not more, they would sure send their own men to find before pirates but they don't want no one.
The biggest battle can happen before reaching there then they find it and can reset the verse with the special mechanism that exists in Laugh Tale.
This is also possible against your point that it should be via battle only not with something else.