I can't claim to know, but the game got a pretty big update last year and another one just recently. Before that, I think there was a quieter period regarding updates.
Personally, I've returned to the game due to circumstances in life. Well, 'returned' is not a great word, because this is the first time it feels like I've been able to invest a sizeable amount of time into the game. As a result, in a way this is my first time really getting into the game despite wanting to even earlier. Anyway, for me it's just a coincidence that it occurred just when the game was getting so popular again (or at least people claiming it is).