I've got an old-ish phone, so in most cases, I can't download your app even if I wanted to. You deliberately set your minimum iOS deployment version to be higher than what my phone can even install. So I have to go to your web site or just stop doing business with your ass. Just because your developers decided that developing for older phones is too hard to figure out, or it takes too much effort, and they'd rather just cut us off.
I think the blame is on Apple here, you can't support older devices even if you wanted to. (And it's the same on Android)
You can support older devices, but admittedly Apple does not make it super easy to find. The easy "happy path" in Xcode is to only support the most recent OS versions.
iirc even then there's a minimum that xcode will still deploy to. The only way to have an app work on older versions than that is to not update it at all