And the AD counterparts dont even need to build mana items.
As someone who mains adc and secondary mids I take issue with this statement. First of all AD counterparts don't need to build mana items because in order for their main source of damage to be relevant they need multiple items including at least one crit item and infinity edge for some ADs and 2 zeal items for most. If ADs had to build mand they would be completely irrelevant until late game and would massively decrease dps making the role irrelevant. The AD role is the latest spiking role and building mana items would further increase that and also decrease the one purpose of adcs which is to provide high consistent damage late game.
How would you feel if the ADC have limited ammo to do basic attacks?
Giving ads limited ammo to do basic attacks is a terrible idea because how would ads last hit? How would they get gold to become relevant? How would they teamfight late game or destroy baron or structures with limited attacks. This would completely nullify the ad role.
or if we gave huge mana costs to every AD champion even those that are no cost?
This would give way too much power to supports in lane phase because ADs like Lucian and Xayah wouldn't be able to contribute to early game trading. This would further the problem of ADs being super weak early.
Would you still cry about spamming abilities after you had to waste your time and gold buying items that will let your champion do his job properly or even farm because mages farm with abilities you know
Many mid laners have items that have mana or mana regen already in them. It's not like adc where most adc items give no mana regen. Furthermore you don't need to farm with abilities. You need to wave clear with abilities if you want to get rid of the wave as fast as possible but in terms of farming you can do that with auto attacks if you are good enough.
Be happy that mages build mana instead of ap.
Mages rarely have to choose between no damage and lots of mana so I think this is a hasty generalization and anyway if mid laners didn't have to build mana and all of their items had more AP they would just one shot every squishy and completely replace ADs. So I am very happy.
Riot also removed the mana potions nerfed the mana overall made into a support item while it was a meta mage item.
This is true however it is counter balanx d by lost chapter and morellonomicon which solve the mana problem for many mid laners.
Everything is nerfed for the precious no skill AD champions so they can shit on mages who actually require skill to hit their skillshots.
AD champions are not no skill at any division past bronze. AD is the most mechanically intensive role in the entire game. While it may seem like just right clicking to many bronze players it is in fact much more complicated with orb-walking, animation canceling, kiting, positioning, farming, 2v2ing, and more. Furthermore since when could ADs shit on mages like it's no big deal. Unless I am a fed adc most mids can kill me mid game and even late game many mids can destroy me. Champions like Ahri, Syndra, and LeBlanc can delete me with champions that need long range skillshots like Xerath having huge range advantages. Furthermore some mids don't even need to land skillshots like Syndra and Ahri.
Riot already favours AD over AP GA was built on mages as well now it gives +40 AD so only AD champs buy it.
I do agree that this was a nerf to mid labels however you do need to understand the context for this change. The item was way too good on tanks and needed to be changed for carries. This meant this item had to either be for ADs or APs. Mid laners have many defensive options like Zhonyas and Banshees while Ads only had Mercurial.
I want to end my response with one more point. Aren't mana costs a good way to judge skill? Is there really a good way to display your skill when you just spam abilities whenever you want after your first back? Having mana costs meant that in lane I could dodge abilities and then punish the enemy mid when they were oom. It also allowed to show mastery on a champion because If you were better on a champion you could better control mana costs. While these mana issues should disappear by late game for the sake of relevance it does add skill to the game. For these reasons I disagree with your point.
Edit: on phone so sorry for spelling errors