I've never been lapped so I really don't know how to take that. I guess if you're that far behind it's unlikely that you're going to improve your position much if at all, however you may affect the leader and I can see why that's frowned upon by many. But being in last (something I'm familiar with) you certainly shouldn't just give up. I could see on a longer race, say a 20 lapper where someone that is lapped could conceivably get back into it.
Are people actually getting lapped on typical 3-6 lap races? I mean are they getting lapped while racing and not just standing still waiting to be lapped so they can take out the leader? I guess I'm neither fast enough to lap someone or slow enough to be lapped.