This snippet has been constantly criticized and somehow it makes me think that the people who loudly complain about it have never worked in any kind of big company - which is fine but it shows a lack of empathy, experience or both. You can go to any big company around the world and you'll find duct tape because you know what, if it works, it isn't terrible to use/update and doesn't leak millions in lost revenue then there's no valid reason to spend dev time on that.

This most likely was a temporary solution that grew over time and was left like it, they just kept adding new combinations. It works. If you want to add a new combination you just add it and run a migration (or similar, I've not worked on Twitch but I assume it's not the most difficult thing in the world if it's still like this).

I understand that this can feel like an itch that you really need to scratch (I also feel it) but if you literally see the source codes of any big company you'll find stuff that anyone can criticize from their chair with little effort. Let's now go build a tremendously successful platform like Twitch without cutting a single corner ever and see how that goes.