Come to think about it, Gangplank and Poppy are actually BALANCED
No, not underpowered. Balanced. They have a clearly defined weakness in their early game dependency on items, but once they actually purchase some damage items in order to DO DAMAGE (What a concept!) they can carry the game if played well enough. None of the molly-coddling mobility meta creep, none of the ridiculous base damage that you see permeate League.
Just solid, oaken Dota-level carry semantics. Hell, on that same coin Yi and Tryndamere are basically the same as well.