The minions are actually pretty deadly, especially watch out your ally minions. They will always look out for when you're the most vulnerable and in need to escape ASAP, and proceed to charge at you and pin you down. Little pricks.
That said, minions do actually do significant damage in the early game, this is especially true if you're playing melee as you tend to aggro more minions since you're at the front line.
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Baron is also pretty deadly in mid-game. It could easily overwhelm and team-wipe most of the average teams in the mid-game phase.
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The claims on the turrets and drag aren't wrong tho. Turrets are only really threatening in the first 3-5 levels, and drag could be worse, as many reasonably well-prepared junglers can solo it since level 2-3.