Cope. It's a better card and it's being more used because of that. Those players are the official tryhards. They won't overlook a card just because it costs money. Enemy Controller is the best staple.
Fact 1: Econ is a free card and very early available
Fact 2: The usage of Econ on higher ranks drops significantly
Fact 3: The usage of Main/Mini Box staple cards on higher ranks increases significantly
Conclusion: Econ is good for beginners but advanced players usually replace it with better cards.
Fact 1: Doesn't stop "advanced players" from using it. Nothing locks you from using it other than the banlist.
Fact 2: Cope. The popular cards list is for Platinum and above only, and it's there very high on the list. It has also been high in absolutely every single KC Report.
Fact 3: Using them doesn't stop them from using Econ.
By being a quick-play spell alone, makes E-Con better than traps.
Imagine it comes to your turn, you have 1 lv4 monster in hand and opponent got Blue Eyes Ultimate on their field. In a situation like that, drawing staple traps is good, but drawing E-Con will result to victory.
As with Book of Moon, E-Con can be used as offense and defense, while Book can only for defense.
You can use Book of Mumbo Jumbo for offence by attacking a defense position monster you flipped down with it but Econ can do the same thing by turning them to face up defense instead of face down.
You’re saying unlimited is better just because you can put 3 in your deck? The difference to 2 is very small in a 20 card deck and when both are hard to search.
Sure, you can use it. But this means you can't use Hey Trunade, TTH, Conentrating Current, Kiteroid or Neos Engine. Lightsworn Engine also doesn't work that good.
Also, there are way too many archetypes that have a card in limited 2.
That’s all true. But to be on a list with those top level cards proves Econ is a top level card as well. And worth choosing among them for your 2 slots of limited 2.