Let's explore the assumption that droprate manipulation occurs close to thresholds (the 99/100 being the classic example people give) in conjunction with the fact that droprate tracking puts the average at 33%.
There's only one way in which you can be negatively affected by this and that's if you are easily frustrated and choose to spend to relive that frustration. If you just accept the fact that farming slows down at 99/100 and carry on doing your normal amount of sims per day then the inclusion of dynamic drop rates has exactly zero impact on you.
If you also come back to reality and accept the fact that with a flat drop rate you will very regularly be stuck at 99/100 getting a string of zeros, you'll realize that they don't need to implement drop rate manipulation to frustrate a great number of people that post on these forums ;)
In the end we'll probably never know the truth, so just play the game and stop worrying about it.