Exactly as Jock wrote.
I fear that no one is capable of designing a game that would balance the efforts of "hardcore" gamers, who treat the game as a full-time task, and the rest spice it up by using bots, quickly going through the entire designed technological progress, and all that remains is PvP (which is not super engaging or interesting), or arranging life around sieges and taking over provinces for better kingdom buffs.
Resetting the game every 3 months will cut off casual players (of which there are not too many to begin with) here I wouldn't expect there to be many if after years you are aware that your farm, which you've been paving for the last 3 weekends, can be destroyed by another player who spends their entire life in the game, and your character gets killed because it happened to fish at the wrong time and place. Who in their right mind would invest time (and money) in such a game?
The game has many toxic mechanics that require from players an extraordinary level of engagement and arranging their lives around activities in the game. Here, I agree, for example, waiting for taming animals, obtaining steel, or the previously mentioned sieges and conquering provinces.
(translated by chatgpt cause I'm lazy)