Op didn't say anything about such people downloading the browsers. Their children or associates can do that. The point is, that an automatic unskippable system update will change the settings the child has done for their ill parent. The parent won't understand what happened or at least won't know how to change the desired setting back.

This is a bit of tangent, but hear me out, if the user was blind, for example, and was using some specific accessible tools, it would be really bad if the OS decided to change the tools by itself. The end-user would have no way to use their computer anymore. At least until a healthy person could revert the system settings back to their old state.