Thanks for the link, but while I am searching now even on bitcointalk there are many members said Kucoin ask for KYC compliance even if their limit is below the level what they mentioned for non verified customers and also some account under froze until they complete KYC so with any centralized exchange regarding KYC or no KYCed account the user should be asked to verify their Identity at anytime which is also mentioned in their ToS so yes there is no guarantee that someone can withdraw as non verified user forever.
Requiring KYC is possible under certain conditions since it is really a centralized exchange like suspicious activity detected. I'm a regular user of kucoin and fortunately, i never experienced requiring KYC yet.
While other exchanges have accounts limit, 50k limit for level 1 is really huge. But nah, i found lots of complains about polo, shattered reputation in those years that i decided to ignore them and only use kucoin even though it has lower withdrawal limits.
Even myself had very bad trade experience and due to that I almost lost half of my capital value which mainly happened due to their fake trading volume so I simply decided to sell for whatever the price and stop using the Poloniex anymore and that is the end of the story so instead of trusting their no KYC better choose the right exchange with lower KYC requirements like only name and address for level 1 in case if we are only a moderate trader and don't want to submit more personal information.