Well when it comes to the trading then you have to submit your KYC's all the time over the exchanger to increase your trade limits and withdraw limits as well. I guess it is pretty normal to have this and also it increases security of our funds or accounts too by showing that it is us! I think when it comes to the non reputed exchanges which are asking for the KYC then it could be somewhat frightening to give away info over such small exchangers. I guess there are wide variety of options we can follow to save ourselves from giving such information. Fro example using decentralised exchanger, or keeping fund in the private ket owned wallet and then transferring them over the exchanger at the time of trade.