Sure but they were punished by social pressure or gkicks. Nowdays you dont.
Its not like you could go to raid selecting "yeah im healer", be afk follow and die due that and still get rewarded loot and not get punished at all.
Maybe get kicked from LFR if someone cares enough (not many do) and just queue up next time cooldown goes off.
No one will know cept those 24 randoms. No one aint gonna gkick you over that.
Edit:
Or am I confused here ;P