I have seen evidence of some scams being run under the guise of KYC in order to gain your passport and government issued id's. Be careful out there and remember that a lot of these coins end up being scams. Do you really want them having your passport/photo identification? This is how people fall victim of identity fraud so please think before sending your information in.
Of course, it is not necessary to send a passport, as it is used to identify the identity of fraud. Send other documents with a photo - this is an ID card or driver's license. Of course, check the company where you provide personal data.