I've seen plenty of "write C/Java in any language" folk, working with them wasn't something I enjoyed and usually tried to distance from the mess. A few of them were domain experts but the codebase they produced was a nightmare to work on.

I've swapped a decent number of tech stacks throughout my career. When I haven't used a stack for a few years it took months to get up to speed. Especially at a senior level where I should be capable of making design decisions, codebase level technical improvements, team workflow optimization, etc.

Obviously domain knowledge is important but I wouldn't trivialize technical side.