Triforce gives more GENERAL stats, but that doesn't matter if it does less for the champs who buy it. Your argument there is literaly the same as saying "Runic echoes is bad on Hecarim because it doesn't give AD". It isn't relevant and it's not saying anything relevant
Sheen won't be procing faster than what Shiv will for the majority of 20 minute games and for the majority of 40+ minute games.
Shiv's 0 AD doesn't magically make it not overpowered.
Earlygame, Shiv can deal up to 300 mixed damage before Armor/MR.
That damage goes down to around 250 after Armor/MR but that's over 1/3 of most ADC's healthbars at around levels 6-8(the time in which Shiv is usually finished)
Trinity takes longer to buy, RARELY will ever proc for equal DPS to Shiv(Only Nasus and Yorick can reach the same DPS), is at a static damage amount(will never change),doesn't cover any weaknesses whatsoever, and Trinity isn't going to get much better than what it is after it's been bought
Shiv takes 1/2 of the time Trinity does to buy, can be procced more often, almost never falls off, has more DPS AND burst lategame than Trinity does, Has more burst than Trinity earlygame, has a change-able damage amount, will ALWAYS get better after other items are bought to help it out, AND covers ADCs weaknesses
How is this fair?
one of the main weaknesses of ADCs should inherently be waveclear because if that isn't an inherent weakness then ADCs will be able to do everything and therefore will not have a single strategic niche
Riot has circumvented this by allowing ADCs to have Stattik Shiv
Okay so Riot wants to give some ADCs waveclear... but then why does Shiv does equal/more burst damage than Trinity does from the early-midgame?
That would only mean that Riot wants ADCs to out-burst the champs who buy Trinity force...
Shiv also does more DPS than Trinity(again exceptions being Nasus and Yorick) which leads to a huge problem...
If I can get all the burst I want from Trinity but then decide to instead opt for Shiv... the only thing I lose out on is some mana and health
The health can be solved for with lifesteal and the mana can be solved with Essence Reaver
This means that ADCs can, if they so choose, have no weaknesses except for what is inherently in their kit, and Assassins(Plus the Assassins have to work three times as hard to do the same burst that most ADCs can get in 3-4 basic attacks from 10 minutes into 40+ minutes)
This makes ADCs a game-warping class that should NOT be as powerful as they currently are...