Every person that says this has to be completely unaware of all the tools available to them; Party list, enmity meter, focus target. You can see every spell cast by a character, it's in their cast bar. You can see how much hate someone is generate, and what spells they are using. it's in the party list. With this information you can very easily tell when mages aren't doing their jobs. Physical dps have a bit more transparency but you can look at a drgs skills and see if they are keeping them up, or a mob to see if a monk is keeping up dragon kick and it's dot's. You can also watch a physical dps rotate around the mob or not. A third party program is not required at all to see when someone is doing bad. read the personal story it should shed some lite for you.
personal story of similar to op
you have a cast bar. every person in the party can see exactly what your rotation is. I was in Brayflox on my blm and had another it took us a little long to kill the first trash which I thought was weird then next thing I know boss isn't even at half hp and we are up to 4 bombs. at that point I pay attention to the other blms rotation for 2 cycles. while casting all my spells and dodging. It was fire 3 -> fire 3 -> bliz3 -> bliz 3- Thunder 3. When I asked why they are not even casting fire 1 or even casting the one mroe fire 3 they could they replied with don;t even start I play how I want.... well you aren't playing in fact you are harassing the party. This resulted in his dps being so low we almost enraged wiped to the first boss of brayflox HM. if it wasn't for me playing the job right or if they would have had a lesser geared player as the 4th they would have failed the dungeon. There is a difference btwn playing how you want, and being worthless. his dps was so low that even without a dps meter I can tell you it was lower then the warriors. we carried him through the dungeon, gave him free myth and soldier, and he did nothing to earn it at all, and you are calling this ok?