> I think you may be underestimating the "language barrier" for more junior devs.
I know people like that. Once junior devs, too back in the heyday of Enterprise Java in the late 90s they couldn't be bothered to learn this ugly upstart language known as JavaScript because "serious developers don't use a toy language like that". In part, who can blame them? CS professors at that time floated ideas like object-orientation and code generation being the be-all and end-all.
These developers sometimes went at great lengths to avoid writing the tiniest bit of JavaScript at all (when it 'finally' became obvious that this newfangled web thing wasn't a passing fad ...) and invented convoluted frameworks that generated JavaScript from Java code. These frameworks inevitably couldn't keep up with the pace of change in the web development community at large, which is why nowadays they often are a huge technical debt to the projects they're used in.
The developers themselves, now not so junior anymore, often have a hard time finding a job today because learning something besides Enterprise Java was too much of a hassle.
So, while the idea of "easing in" junior developers by having a consistent language in all layers might have some merit, in the long run it might very well be doing them a disservice and also leave behind a huge pile of technical debt in the end.