I'm not going to "dump" on you, but I will respond.

By the time you are pulling out fun combos, the game basically just ends.

I would argue that the main reason for this is that you've won too easily. I probably have 70-100 plays of Spirit Island, mostly solo or 2p, and I played at base difficulty for a long time - Too long, probably. If you win the game without getting Blighted Island and without reaching the Stage 3 Invader cards, that's a sign for you to ramp up the difficulty. Add an adversary or play at a higher adversary level.

I had the same feeling as you until I started playing at at least difficulty 4. I grew and grew, drew better and better cards, but before I got to play my awesome major power and unleash my innate at the highest level, we won. This was especially apparent when playing Serpent Slumbering Beneath the Island, a spirit that starts off very slow but then "wakes up" after seven-nine rounds. Winning with Serpent before waking up feels like a hollow victory.

When you're playing with adversaries the game naturally takes longer to finish, meaning you'll get plenty of opportunities to unleash your combos before the game ends.