Why dissassemble entire phone to replace broken glass?
I need to replace the broken glass on a Galaxy S8. The LCD and digitizer are still fine, so I really only need to replace the glass, not the whole screen. Since entire screens are still $200 but the glass is just $20-30, obviously I want to replace just the glass. Although I haven't found a specific guide for that here on ifixit for just the glass replacement, there are plenty of YouTube videos of the process. One thing I don't understand is why they take apart the whole phone first from the back when only replacing the front glass. Can anyone tell my why that's important?
It seems to me I should be able to just apply heat directly to the front glass and take it off, then just glue a new glass on. I'd really prefer to not worry about messing up some of the internals.