In China, MySQL is the mainstream database, postgresql is too small, so as soon as possible to support the MySQL protocol
As far as I have read CRDB won’t be supporting MySQL Protocol, and it was a decision to go with the Postgres Protocol as it was better documented.
Also one of the main reasons why CRDB chose Postgres Protocol was because of the license the Postgres Protocol is under ie. “a liberal Open Source license” not the GNU license that MySQL Protocol uses.
You can find in the following link the reasons given by CRDB itself :
In China Baidu uses CockroachDb:
So I guess not supporting MySql protocol or syntax is not going to be a hindrance.