As
@camocorvette said, I am also a fan of backups, and I like hard copy maps. I learned to use a map and compass with my dad, but it was also part of the grade school curriculum where I'm from. I'm also not pushing one way or another for what anyone else does.
-I agree that battery life could be an issue. Not specific to phones though. I bring extra lithium batteries for handheld GPS, and I have a portable charger for my phone that can recharge my phone several times (3 or 4 depending), and a single charge on my phone can last 2 or 3 days out in the field.
-The resolution on the downloaded maps is pretty good. To the point that I could pick out trees or bushes near me. It's definitely different than a paper map though.
-OnX does have a tracking feature. I don't really use it, and couldn't tell you if you can change the frequency of setting points. You can also always add waypoints whenever you want, which is usually what I do with either a hand held unit or a phone. If you have some specific frequency that you prefer points to be set, that could be an argument against the phone (maybe?).
-Not downloading the maps in advance is not a phone issue, that's a planning issue with the user. It would be like bringing the wrong paper map.
I think sometimes the fear of electronics gets taken a little too far (not saying that's you or anyone else in this thread). It would almost be like saying paper maps are bad because the wind can blow them away or they can catch on fire or you can't see them at night. At the end of the day, a dipshit is always going to get lost not matter what they bring. No matter what, know the limitations and have a backup if you are going out in the woods.