The other half of the argument which you fail to consider:
Can you tower dive?
What is losing lane? Down in kda doesn't equal "losing lane" contrary to popular belief. There's cs, levels/xp, etc. to consider too. Also... how many times has the person been ganked? If they're just barely losing and they've been ganked a dozen times (exaggerating, although I've seen it happen many times) then they are essentially WINNING lane all things considered.
Can you take tower?... What about just forcing the enemy to base, miss a massive wave of xp and cs, and say... invading to steal an enemy buff off that pressure or get dragon or herald? Hmm. That would be meaningful too.
Are gank paths warded? No. There's always a route into lane that isn't warded if you aren't too lazy and unimaginitive to find it. There's at least 7 routes into mid, 4 in bot, and 4 in top. Figure it out buddy. Bot can generally ward up to 2 of these routes at a time. Mid... 2 if they use a control ward; kill control ward, now they just have 1 path warded out. Top? Same thing as mid - can ward 2 if they use control ward, so kill it and come back.
Lazy afk farming and thinking your 10 cs lead over the other jg is going to carry the game as he's spending half his time in lane putting his WHOLE TEAM ahead is the height of stupidity. Even a failed (but decently attempted) gank here and there sends a message to the other team and makes both their jg and their laners have to play more respectfully. Even a nocturne who "needs level 6 to gank" can get off one or two successful ganks at minimal cost before level 6.