Totally disagree, I've used KQL for about 10 years now, and SQL for 20. Given the choice, I'll always prefer KQL.
Sorry, I don't have time for a thorough rebuttal of all the topics mentioned in the link you provided, but if I had to bring up a few counterpoints:
1. (Can't be expressed) KQLs dynamic datatype handles JSON much better than SQLs language additions.
2. (variables/Fragile structure/Functions) KQL fixes many of the orthogonality issues in SQL. (Specifically: both variable assignments and function parameters can accept scalar and tabular values in a similiar way, where-as SQL uses different syntax for each)
Sorry, I don't have time for a thorough rebuttal of all the topics mentioned in the link you provided, but if I had to bring up a few counterpoints:
1. (Can't be expressed) KQLs dynamic datatype handles JSON much better than SQLs language additions.
2. (variables/Fragile structure/Functions) KQL fixes many of the orthogonality issues in SQL. (Specifically: both variable assignments and function parameters can accept scalar and tabular values in a similiar way, where-as SQL uses different syntax for each)
(disclaimer, msft employee)