Once Steve Huffman told me at a conference that the developer who developed Reddit Enchantment Suite(RES) worked at Reddit upon asking him why reddit user interface was so terrible when there were already things like RES to take inspiration from.

According to him the employees at reddit were not allowed to use RES so that they could strive to make reddit better rather than making Reddit with RES better.

We never saw reddit get better in terms of UI, it only got worse with new reddit UI they came up with. They might as well let their people use RES since improving the user experience was clearly not their priority.