There are numerous fallacies in this. They have the same SoC, but an SoC isn’t the whole computer. Also, the batteries are much smaller and the thermals are much worse than a MBA. It’s also a touch device whereas macOS and all of its apps are touch hostile. Sure it could run macOS, but it would suck badly. Craig F. even said so years ago, saying they had macOS running on iPads. They tested it and found the experience to be pretty bad. Apple doesn’t deliberately ship awful experiences (note I said deliberately).
Aside from bad user interfaces, Apple spent years implementing battery saving techniques, such as not permitting background operations and indirect server-based notification methods. Stick macOS on an iPad and all that goes out a window. If you want an overheating device with a 2-hour or less battery life, go for it. It’s indisputable an iPad is a lesser animal than a MBA, something everyone acknowledges is for light computing and not for ultra-powerful apps. Yet somehow people here seem to think a lesser device than a MBA can be turned into the ultimate laptop that competes with a high end MacBook Pro. The Pro name just means it’s the highest end of the iPad line. That doesn’t make it on the level of a MacBook Pro. The lesson here is be careful of what you ask for. You might get it… and regret it.