The design of your website in Reddit's case has nothing to do with scale. Shitty UX will always be shitty UX no matter how many users are on your platform.
>The design of your website in Reddit's case has nothing to do with scale
Sure it does. Once you reach a large enough scale you kind of need to do stuff to attempt to not be losing money on the development & hardware costs of such a large platform.. so you end up changing, even if it's not 'for the best'.