I wouldn't say these are no-KYC exchanges, because some of them have checkboxes on their sign up pages reading "I am not a Politically Exposed Person", "I am not a US Person", etc. which seems to strongly imply an ID check is going to be waiting for you immediately afterwards.
Did you see the post date? That was a year ago, now the situation has changed, for example, ByBit is no longer a no-KYC exchange. The rest of the exchanges work fine without KYC, especially OKX and KuCoin. I am a regular user of these exchanges and no blocking or identity checks are carried out there.