It's not about whether you are willing to go the extra mile and level herbalism to 225, get AGM, and have 800 heavy runecloth bandages ready to waste in every arena. These tools benefit some classes much more so than others.
My classic example is a hunter v. shaman duel. Now just assume that both of them have 225 herb, agm, and unlimited bandages to use.
The hunter's only chance in winning is to burst the shaman down as fast as possible. He cannot hope to outlast the shaman. Not to mention, his pet will die soon and he cannot afford to keep healing it and keep the same dps output without going oom very fast. In short, the hunter must kill the shaman quickly or else he loses.
225 herb benefits the shaman much more than the hunter. This is because it forces the hunter to dps through even more HP. The lifeblood is useless to the hunter because it will not help him outlast the shaman. The hunter's enemy in this arena is his lack of sustainable dps, not his health points.
AGM benefits the shaman as well because it is yet another way to stop hunter DPS, causing the hunte to go OOM before he gets the shaman down. On the other hand, AGM is not useful to a hunter at all. In addition to the points I made earlier on lifeblood, the shaman can simply purge it off.
In short, the fight would be much more fair if 225 herb and AGM were not used by either side because the two are much more beneficial to shaman than it is to the hunter. With these two things on his side, there is no possible reason why a hunter should ever be able to beat a shaman. But without, it is a much more even-sided fight.