You say that, but plenty of job adverts are for fullstack developers, e.g. backend experience in C# with dapper or EF, and frontend in Angular or React. It's not an absurd transition for an experienced developer, even if there is a learning curve.
As someone who works with database engineers, there's also a world of difference between the ones that know what they are doing and the ones that don't.
I was internally retasked from python to java full stack development. I have a bachelors in computer science, it's expected that I can just pick up, with a little time, any tool that fits the task. 95% of software development is just connecting pipes together. We are glorified digital plumbers for the most part, with only a few people working as the equivalent of civil engineers actually doing important design work.
If you chose to save a few bucks by hiring limited devs, that's a choice you made. In our orgs, the guy who moves CSS boxes for a living absolutely can write some SQL queries. Most places don't write database code, they write code that uses an ORM or other framework to interact with existing databases.
