Why is Zoe available to get purchased lv1 while most Summoner Spells have a Level Cap?

Titel basicly. So beginners get Flash and Teleport lv 7, Cleanse, Smite and Ignite lv 9, just Heal and Ghost are have available at lv1. But people can buy zoe already at lv1 and with her w Spellthief beside some quite interesting items you can get no one at this level realy knows how to use like redemption, you can also get every summonerspell. For me it is hilariously to see a Heal Ghost Zoe. I know basicly it is to assume that not beginners but rather quite smurfs purchase this champion or that in league till now there was not such a thing about banning certain champions for certain early levels, but zoe could be such an exeption. The summoner spells level cap is to get each summonerspell introduced level after level, to have a chance to exploit them and not already have to think about how to use smite or flash at level 1. But still zoe can do that. So why not make Zoe just available at lv9 to get purchased? Sry if now some smurfs will hate me for that idea, i just wanted to see that from the perspective of a beginner (had a friend who told me about that). And not only for zoeplayers, for enemys who play at lv 4 or 6 vs Zoe its quite difficult to understand her movements too.