Nope....

1-)Soldiers cost time and money to train, equip, and organize, even levies. You need to go out find men, give them the news, in a few days they have to get report back. Then u gotta group them, assing a commanding officer, deal with logistics and stuff they carry, etc. Everyone took time to get ready for combat, some more than others.

2-)The AI would spam you with troops in the 1st few turns, $ scripts and populations refilling at work. Also, the AI would then have $0 to make any buidings. However, it will outnumber you, and when u kill a stack you free up $$ for another stack that same turn. No good