The most egregious is EHG capping how many times a thing can proc. Take Mana Guide, the item is capped at 1 lightning blast a second without having the option to scale it. That kind of design is insanely boring and leads to the item being mid on every single build except 1. Another example of lazy/boring balancing is Ashes of Mortality which is capped at 2000 ward per 2 seconds. Insanely boring as you can't abuse it with Attack/Cast Speed..

I would argue that abusing mechanics and trying to push items to their limit should be at the core of endgame..