You might be eminently qualified to do the work but in reality no one works in isolation (unless you are Joe Hewitt [0]). So unless you can mind read, no one can say for sure if you will fit in with the existing culture to get the job done, a subtle aspect many people overlook.

A good example of a qualified hire quitting just after six months is Chris Lattner who quit because "... Tesla isn't a good fit for me after all." [1]. You are free to Google the personality clashes which made it difficult for him to continue at Tesla.

[0] https://medium.com/@joehewitt/entrepreneurship-or-lack-there... - original deleted but archived from Google's cache here: http://archive.is/1aDdk

[1] https://twitter.com/clattner_llvm/status/877341760812232704?...

That uncertainty is always a given... addressed in the first three words of "it looks like you'll fit in". I still don't see how that can be perceived as offensive or insulting.