if only ???

[jesson cui]

THERE is nothing more frustrating than turning on to a motorway and getting stuck in a traffic jam that stretches into the distance. Why did the radio and the motorway-entry sign offer no warning? The satellite-navigation system shows a different route—once you get to the next exit. But it leads through the middle of a town and could be heavily congested, if only because other drivers are taking the same detour. Perhaps it is wiser to stay on the motorway and hope for the best? ---- from eoconomist ​

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if only because other drivers are taking the same detour. what does "if only" in this sentence mean? thank you！​

 

[albertino]

THERE is nothing more frustrating than turning on to a motorway and getting stuck in a traffic jam that stretches into the distance. Why did the radio and the motorway-entry sign offer no warning? The satellite-navigation system shows a different route—once you get to the next exit. But it leads through the middle of a town and could be heavily congested, if only because other drivers are taking the same detour. Perhaps it is wiser to stay on the motorway and hope for the best? ---- from eoconomist ​

if only because other drivers are taking the same detour. what does "if only" in this sentence mean? thank you！​

"if only" has two definitions:
I) used to express a strong wish, especially when you know that what you want cannot happen; or
II) used to give a reason for something, although you think it is not a good one.
Which one do you think fit?
(Not a teacher);-)