I must respectfully disagree, as your advice is bad.
Keep the damn lifelines!
As will many, I'm sure....
But my point was, and Semi Jim made it as well, that they are not really "lifelines" in that they are unlikely to save anyone on their way overboard. On most boats they are 18-24 inches above deck at best, right around knee height - not an effective restraint unless you are already on your back.
Furthermore a 200 pounder falling across a boat into the lifelines could well break/bend/tear out stanchions on many more lightly constructed boats.
However: They ARE places to grab hold, they DO keep small persons and children within the confines of the deck, the DO help keep sails on deck, esp if netting or lacing is added.
Is it possible to run a boat without them? Absolutely, if the above mentioned aspects are not considered crucial.
BTW I have lifelines and stanchions on our current boat, in fact have had on all our boats other than the one mentioned above - and have no intentions to remove them for the reasons stated.
The question was - could they come off - and under certain intended usage and conditions I'd say yes they could.