It seems that in a high level Pokemon Go gym (level 8+) the bottom-most Pokemon are the most important -- because if an attacker can only take down one or two Pokemon, then the Gym's prestige is only lowered by 500-1000. For high level gyms, you need to lower the prestige by 10-12,000 to even kick out 1 Pokemon, thus it's unlikely that an attacker is going to attack 10-20 times to take out the bottom Pokemon, and then do it again for the second bottom Pokemon and so on.
Doesn't this make them more important than the other, higher Pokemon in the Gym?
The bottom Pokemon are also the first to be kicked out, if the prestige of the gym is lowered to a certain level. There might be higher CP Pokemon in that gym with really bad moveset, but those movesets do not really matter, because the attacker probably won't get to the top or second Pokemon that easily -- if the attacker can battle them, that means the gym may be at a lower level, such as 4 or 5, and the gym is easily taken down any way.
(One example is, if there is a Gyarados with bad IV and bad CP, but with Dragon Pulse or Hydro Pump, at the bottom of the gym, then it can defend the gym really well. Versus, a Gyarados with good IVs/CP, but with bad charge move: Twister, and at the middle rank inside the gym. it can stay at the gym longer, because it can't be kicked out that easily, but at the same time, it really cannot defend the gym that well (Twister is only 1/3 of the Damage Per Second compared to Hydro Pump with STAB considered)).
So is this true? Are the bottom-most Pokemon in a high-level Gym the most important ones?