Why does Ashe demand red buff?
This is a question that in itself has a lot of merit, but also mirrors quite a lot of other things that is a problem in the lower elo community.
People just tend to blindly accept standards. For example, Red buff MUST go to the ADC after a certain point of the game. Meanwhile, red buff is applied when auto attacking, and the effect stays there for some time, regardless of if you auto attack again or not. Therefore, even though ADCs have the best way of applying it, it's not a must have, and definitely wasted on Ashe.
Ashe already slows with her basic attacks, and that slow is much stronger than red buff's. So why have Ashe pick it up? No reason at all. Also, the burn damage isn't the biggest of damage either, so not applying it constantly won't matter as much.
Do you know what else Red Buff grants? Huge HP regen after level 11. Do you know who wants HP regen? Frontliners and champions who don't have access to other sources of health regen. Guess what. ADCs almost always have a reliable source of healing, therefore, red buff's healing is, again, wasted.
How about a red buff on someone in the mid lane, like Viktor? He also has a potent AA to apply it to the enemies and can also heal back some damage. And in the case of Ashe, to answer my question, she already has a slow in her kit and she already builds lifesteal, be that either through BotRK, Mercurial Scimitar or Bloodthirster.
Let someone else who actually has the need to heal up have the Red Buff in some cases. How many times has your mid, top or jungler been poked out before the fight starts and they would love it if they were able to regen to full health?
I remember a time where Red Buff's true damage was an on-hit buff. Basically, every AA you would land would instantly apply the true damage and renew the duration. That was a time where having the ADCs have red buff was important, because it was something like a mini BotRK combined with a Conqueror active.
And I'd like to point out other important "standards" of the game, that should not really be standards. Things like "blue buff MUST go to the mid laner", even though the mid laner doesn't utilize mana, or if the top laner or the jungler might need it more. A mana hungry, powerfarm jungler who needs to outpace the enemy jungler, like Graves, would probably make much better use of the blue buff than the mid laner.
What I'm trying to say it, don't blindly follow "standards", just becuse you are told to. Criticize the situation, understand what the game needs. Apart from red or blue buff, the same can be said about runes, masteries, items etc.