Wikipedia has a decent critique section [1] which enumerates the points that GP seems to be making.

Of course, these are academic critiques which vary widely - none of which would support the assertion that the model is "not useful scientifically".

I'd be very surprised if any of the qualified academics that critique the Big 5 model would make such a claim.

[1] https://en.m.wikipedia.org/wiki/Big_Five_personality_traits