But many people aren't going to follow those routines. It's my impression that deadlifts and squats aren't good exercises for this use case because of the danger they present.
Sure, they might be "completely safe" when "done correctly", but somebody using an app and trying to mimic exercises they see in videos or pictures is only guessing at whether they do the exercises correctly. To build muscle you need progressive overload, but that also means that "doing the exercises correctly" gets even more difficult. With most other lifts it's not that big of a deal, but with squats and deadlifts the weights get really high. A dropped barbell with squat weights can easily lead to injury. Hell, it can lead to injury when it's even just lifted the wrong way.
And when you remove those two lifts then a lot of 'standard full body workout' regimes don't work anymore.