I have started a couple new guys recently to have some fun and I have noticed people invading me at what I think are really low levels.
My first reroll I am sl 21 and I get invaded in 2-1 by a dude wearing monk headwrapings, and insanity catalyst, it made me laugh because is poor mana pool was so little.
Last night I roll a new melee type and I am sl 14 just beat Phalanx and am starting 1-2 and I get invaded. I off the dude but I felt like messaging him and helping him out. The least he should do is take off his armor so he can roll.
After that the invades continued most of the night.
I am not sure what they gain by trying to invade that low, maybe they think they can roll noobs but I think the majority of the play base at this time is experienced (even if playing a low SL char at the time) with a minimal influx of new players.