I get that it goes against the fundamentals of crypto currency, but exactly for what reasons though? Assuming you're not using it for anything illegal (if you are then it's understandable), why the concern? I'm asking specifically when trading.
It simply goes against the privacy of an individual whether a trader or not. The online trading is suppose to protect your identity against theft because you don't know the next person, hackers are everywhere also. The reason also is that decentralised and digital economy doesn't really require the data disclosure of the next person, you need to be careful with who you are dealing with because it is not a safe environment.
Right, given that you are trading online, its most likely that you want to stay anonymous by not sharing your personal identity. Because if that's the case, then you should have gone out and just wait for the possibility that sooner hackers will start stealing your personal datas. But its not the case. As long as you are trading with cryptos that are supposed to be decentralized, then you will also expect that the thought of being in controlled by any group or entity will not be possible. But whether we like it or not, most of the exchanges today are now becoming centralized and its a requirement to submit KYC for legalization.