Problem: Klei is determining what is "fun" for the player and forcing it on the entire player base.
Question#1: Is early game grinding the only way to win?
Answer#1: At least at the early prestige levels, no, it is not. The game can be won by organically playing out the encounters.
Question#2: Does early game grinding guarantee a win?
Answer#2: No, it does not. It might increase your efficiency and your chances but the game ultimately comes down to the random cards generated to build your deck from.
Since you can only end your run through death, death only comes during combat, and combat is guaranteed at the end of each day in the form of a boss battle, the only deck that really matters is combat. Even if you cheese every negotiation (20+ card Negotiation Deck anchored by Scorched Earth), you still die at the end of the day if you did not build a synergistic combat deck. The nerf to both battle and negotiation "stalling" only hurts combat decks. There are very few combats (fleads encounter) you can infinitely stall to farm cards. You can drag out multiple combats but you are also risking going in too low of HP for the boss at the end of the day.
By day 3, enemy HP will force at least 6 turns regardless in combat.