Hiring ex C/C++ game developers is fine on the surface. They are smart people and can pick up things quickly.
But as a general rule it fails.
Taking longer to get things perfect is usually not a tradeoff in the webworld that makes sense. People want simple, reuseble and quickly changable features. Pixel perfect perhaps but never code perfect because things change quickly. Why would you hire for that?
Higher salaries for no reason.
Learning curve will be harder than one expects
Smaller pool.
Greater unhappiness. You might hear after writing a game engine that web work is 90% easier but so boring.
Hire an ex c/c++ developer because they show an interest in making a change and are willing to put in the work. Don't hire all of them and expect an advantage..
Also, the typical game is significantly larger than any single gamer experiences, and game developers certainly know the tradeoff of "good enough". Plus game production environment is a technological feat in itself too, and it is those type of game developers that contain the most value - not necessarily the game play developers, but the game production pipeline developers.
I've seen before code where premature, pointless or unclear optimizations used, like dogmatically using stringbuilders or avoiding boxing saving all of a couple of nano-seconds, while the SQL statement is taking 3 seconds to run due to unnecessary sub-selects because the developer doesn't grok set-based logic. Or worse, cursors because they think they need a loop!
Just like I can't imagine the true depth of complexity of game/3d development having dabbled making games in unity, I'm not sure you understand just how complex a sass/enterprise site can get, it's usually issues with actually organising the code that gets you, rather than the code itself.
Your example of i18n is actually quite telling, having internationalized a couple of sites that's actually a fairly simple organizational problem in our codebases, comparatively not really complex at all, just tedious.
My example intended to reference more than i18n, as that only covers the interface. Consider something like an online international university where there is media, but that media varies with 8 different languages, so each and every aspect of any presentation needs to accommodate variable length text fields, left and right and vertical directions of text display, every media clip varies in length due to language, and multi-language users can switch display mode at will. I've done projects like this, over a dozen, and it's quite the challenge.