User blog comment:Care Level/Underlying Systems Rework: Differentiation between Attacks and Spells/@comment-24204000-20140106225936

There are three basic things that make Yasuo's Q ability 'count as an attack', if you break it down you can see the problem with adding all three to a lot of abilities.

1) Applies 'on-hit-effects'

This isn't a big deal. Actually, a lot of abilities already do this. Every AA modififer, and plenty of other abilites like Mystic Shot. Having these isn't a big deal, and the only abilities that this presents a problem for are those where there isn't a clear 'first enemy hit'. On hit effects are balanced around only applying one per attack, so outside of few exceptions (Shyvannas Q in dragon form), they should only be applied once.

Again, not a big deal, already done on several abilities, adding it to more might be cool.

2) Can Crit.

This is big, for two reasons. First, Burst. Abilities often deal a lot more damage than AA, so having abilities crit increases their burst by a huge amount. Abilities that can crit are typically AA modifies, and they only mulitiple the base AD damage. The few exceptions to this are Yasuo's q, which doesn't do that much more damage than an AA per target and does less than full crit multiplier, and Pantheons, which actually 'crits' for a smaller multiplier.

The second problem, is randomness. There is very little randomness in LoL, and adding criting would make engagements depend a lot more on random results. This would be bad, because it makes it harder to predict engagments. This doesn't apply to Panthoen, because his Q either has 0 or 100% chance to 'crit'.

3) CD reduced by attack speed.

This is even worse. This increases the value of attack speed on items, which would require rebalancing them. Attack speed increases per level, so that means cooldowns would have to be balanced with this account.

If you adopt Yasuo's max 66% max cdr reduction from attack speed, you'd need to rebalance all cooldowns around this massive amount. So either you punish them fro not taking attack speed, or potentially break if they do take it, and make all AD casters 'high risk, high reward' champs.

Lastly, if the champ has both 'AS reduction' abilities and 'CDR' abilities, they have itemize for only one of those reductions.

This isn't a problem for Yasuo, because he's one champ with one ability that could be designed with those thing taken into account. Maybe adding some of these three aspects to some other abilties might work, but adding all three across the board is a major mistake.