I believe if there is a tool out there to help then why not use it but don’t 100% rely on it.
What I did like about SkyDemon was the ability to print out a flight plan with magnetic headings etc. So if there is an issue with your tablet for example battery runs out, freezes, you loose GPS signal ( which I’ve had numerous times in the eastern Mediterranean) then either you get your phone out which has the gps ability or you revert back to you old school map.
Regarding using solely maps for navigation how many of us have been convinced we know where we are and then realise something doesn’t quite tie up. Look at the map and there isn’t enough detail or have made an error in the planning stage.
In a commercial airliner there is always redundancy built in. So for one example if one landing gear computer fails there is a second and if that fails manual gear extension.
I fully intend tend to take this approach of redundancy available for when I’m navigating in light aircraft. Last thing I would want is a fine or sending a commercial aircraft on a go around due to my infringement.