The main reason I go anon is because I don't feel like telling people I don't want to group with them constantly. If I want to be in a group, I either put up an LFM or I join a group. If I'm anon and not joining a group or starting my own, it's because I don't want to be in one. Simple as that.
I understand how having a good healer in a group can make quests go easier, but for most of the game they aren't necessary. A cleric hireling and the group members carrying wands/pots goes a long way. Now, I know some quests it's extremely difficult to do without a healer, but I still don't think that excuses sending tells to people who don't want them, I don't care if you're desperate or not.
I can say that because most of the time I run without a healer in group, since my guild of 70 toons has all of 7 clerics and FvS put together, two of which are mine*, one's a melee MC with Monk and only the last four are healers.
*: I don't play healers: my cleric is a Battlecleric and my FvS is a nuker. (Which leads me to the second most annoying thing: Being told I should focus on heals because I'm a cleric/FvS.)