Pool state cannot be easily tracked via event watching

[sblevins]

Events for state modifying pool actions don't include information about reinvested liquidity, so that value must be derived (which is very difficult). This makes it about 100 times harder to track the state of pools

[sblevins]

I'd like to add that it's not as simple as just taking a fee percentage from the input amount, because of rounding behavior when crossing ticks. The final number depends on the number of iterations in the main loop within swap()