Allowing people to choose their own text colors and backgrounds is inefficient and can make text less readable. There ought to be a small set of allowed combinations that have optimal contrast, referred to by simple names.

Allowing people to choose their own fonts can make text less readable. There are only 3 or 4 reasonable choices anyway, so all others should be dropped.

Allowing themes to change window decorations can cause confusion and reduce usability. Let's drop that.

Having more than one window manager available is inefficient and means that more developer time is wasted in duplicative effort. Only one window manager is needed.

Having more than one web browser is inefficient and means duplicated effort. Drop all other browsers.

Having more than one Linux distribution is inefficient.

Having more than one OS is inefficient.

Having more than one system architecture causes needless work.

Supporting any NIC that isn't the best makes the system less efficient. Drop inferior NICs.