Passive is basically a steroid synergizing with attack speed => synergy with offensive items
Q is a dodging tool reduced by attack speed, that is independent on how tanky you are : high synergy with attack speed => synergy with offensive items
W is a flat health regen with % damage reduction, amplified by how low health you are : Anti-synergy with health builds, great to limitate burst so great for.. squishy builds.
E is a true damage steroid on-hit, scaling with AD and since it's on-hit, naturally with attack speed : synergy with offensive items
R is literally THE multiplying steroid, granting additional attack speed which naturally synergizes with AD, on-hit, crit and armor pen => synergy with offensive items once again.
LITERALLY NOTHING IN YI'S KIT IS SYNERGISTIC WITH TANKY ITEMS.
If anything, Yi can have enough damage with highly synergistic items with his kit :
for instance as a core damage, and then build tanky to survive.
BUT HE HAS NO TANK RATIOS OR TANK KIT WHATSOEVER.
0 CC
0 health ratio
0 resist ratio
0 base damage, all of his damage is basically scaling, his Q damage is pathetic and on high cooldown without attack speed. He's ENTIRELY reliant on autoattacks that need.. offensive itemization to scale.