I think I did the math breakdown on summoner school, maybe it was here...
Youre not wrong, heres why.
Five players, each one makes up 20% of the team. Two players in one lane, thats 40% of the team in one spot, almost half the team. If 40% of your team is way behind, and 40% (the enemy bot lane) of them gets way ahead, why would you expect to win? This is further exacerbated by ganks. If a jungler is camping bot lane, and getting lots of assist gold then thats a third player snowballing so 60% of the team is ahead. Next thing you know the snowballing bot lane is roaming mid, and invading the botside jg taking buffs starving out the enemy team.
This cascades into your mid getting lots of allied pressure letting them roam bot/top as the please, invade, taking enemy jg camps.
Dont mean to offend, but stratigicly camping bot is the obvious choice, and anything else is kinda foolish (assuming all lanes are of comparable ability). Also youre correct you can get top lane fed and still lose cause all that amounts to is you and the toplaner getting ahead (40% of the team) and thats going to get YOUR bot lane camped by their jg meaning their ADC, sup, jg all get snowballing (60% of their team).
Its a logistics issue. Theyre getting more gold for their side, and right now the ADC is back to being critical to team success. If you let your bot lane get screwed over, you failed the team. Im not saying ganking top is bad. By all means make sure your top is set up to dominate their lane, but dont keep going back to that well. Repeatedly hit the enemy bot lane, get every dragon, do what it takes to make sure 40% of your team (and 60% with you) are ahead.
Now, if this is how the game SHOULD be thats up for debate, but it is how the game is; bot lane is king.