Hm.. when I first joined I didn't do my last arcanist quest for summoner for a long time. Not really 'on purpose' per se'. Just that the quest itself was hard for me compared to any others. (NPC kept dying). But I stayed arcanist and was able to hold my own against monsters in dungeons every time it was required. Like I never saw myself carried by the other players... So maybe they just don't know how to play or are being lazy?