What you have described is not in any way a problem created by the dungeon finder tool(DFT).
Selfish, uncaring people will be around with or without a DFT.
Even though i spent my time in WoW with cutting edge gear/skills(lol) i never hassled new/under-geared players.
On the contrary, i always let new players learn encounters and was always supportive/helpful. I established a lighthearted, enjoyable tone early and runs with me were always a blast.
A DTF wont ever make me a dlck and i doubt that it has made anyone else.