因为macos不支持
The Mac App Store aggressively promotes free operating system upgrades, even on older computers that can’t install them. Why?
Mac App Store积极推广免费的操作系统升级，即使在无法安装的旧计算机上也是如此。 为什么？
My colleague Craig fired up his 2008 iMac today, because that’s the kind of thing we do here at How-to Geek. While checking the Mac App Store for security updates he saw a large banner promoting High Sierra, in the Updates panel, complete with a “FREE UPGRADE” button:
我的同事Craig今天解雇了他的2008 iMac，因为这就是我们在How-to Geek上所做的事情。 在检查Mac App Store中的安全更新时，他在“更新”面板中看到一个大横幅，宣传High Sierra，并带有“免费升级”按钮：
Intrigued, he clicked the banner and tried to download the update, only to be told his computer is not compatible.
对此他很感兴趣，他单击了横幅并尝试下载更新，但被告知他的计算机不兼容。
If that’s the case why was there a banner promoting the upgrade in the first place?Users head to the Updates panel to install security updates, but this makes that experience frustrating.
如果是这种情况，为什么首先要有一个标语来宣传升级？用户前往“更新”面板以安装安全更新，但这会使这种体验令人沮丧。
To be clear: I think promoting the latest version of macOS on machines running something older is a good thing overall. But why use up screen real estate promoting something that can’t be installed?
明确一点：我认为在运行较旧版本的计算机上推广macOS的最新版本总体上是一件好事。 但是，为什么要用尽屏幕空间来推广无法安装的东西呢？
翻译自: https://www.howtogeek.com/fyi/why-does-apple-promote-the-latest-macos-on-unsupported-devices/
因为macos不支持