not mine but worth sharing

because ADCs don't build any defensive stats and rely on their team to be their defensive stats

if you're feeding all your team's kills into a single unit... that doesn't mean the unit you're feeding into is going to make effective use of the gold.

also - assassins, duelists, etc. are designed to deal tons of single target damage so if a marksman gets caught out due to their damage being dot damage in most situations or critical multiplier damage a lot of times those marksmen will lack the build necessary to fend off an attacker that is able to sustain and duel or ambush.