Yeah excluding computer OS's I have years of experience with side-loading apps on 3 different mobile OS's: Windows 10 Mobile, Symbian(I still own a Lumia 950 and the legendary Nokia 808) and Android(including Google TV on a Sony Smart TV) and I never experienced any security breach or problems. I could give many examples of useful apps I've sideloaded and the objective reasons why and how it was very useful that I had this choice.Sorry but I had to laugh.
I "side load" even if it is a misnomer, on all my other systems except iPhone and iPad.
I think I understand it very well.
Anyway, I haven't really read anything constructive or informative from anti-sideloading comments, nothing that could help me learn something new, most are a collection of huge doom and gloom exaggerations.
At the end of the day the winds of change are obvious, sideloading without unreasonable obstacles will be possible on all current mobile OS's.