Because it's everywhere, has extensive documentation and tutorials, all database tools support it, all relational engines support it, some non-relational engines support it, all programming languages have library support for it, it can be accessed through command line tools as well as graphical interfaces, etc.
You think an industry is going to give up 50 years of infrastructure because some (typically junior) devs think the syntax is "kinda icky"?
> My favorite example which sound easy but isn't - select the row which is MAX(...).
If you look earlier in the comments you will see queries that have "DISTINCT ON" in them. It solves the problem that sounds easy, but actually is pretty easy if you know SQL.
Just bite in and learn proper sql.
But databases aren't browsers. Devs just have a single target usually: whatever database engine the company decided to use.
Still it would be nice to have greater overlap to reduce the niggling details between them that only seem to exist today due to inertia rather than technical necessity.
Actually why limit yourself with SQL...?
PRQL is a language compiled into SQL and makes certain hard-to-do things in SQL easy purely because it allows to streamline operations which SQL needs CTE joins or whatever hoop jumping to solve.
My favorite example which sounds easy but isn't - select the row which is MAX(...).