Using the SAF is quite a bit more complex than simply prompting the user to pick a folder and then using that as your base path, though.
Plus once apps developers were more seriously forced to use the SAF by recent Android versions, I've seen enough bug reports about actual shortcomings and performance problems of the SAF API on the Android bug tracker even for more recent Android versions.
And Google's simultaneous insistence on only allowing inter-app file sharing via content://-URIs has definitively broken all multi-file file formats, with no official replacement available.
Plus once apps developers were more seriously forced to use the SAF by recent Android versions, I've seen enough bug reports about actual shortcomings and performance problems of the SAF API on the Android bug tracker even for more recent Android versions.
And Google's simultaneous insistence on only allowing inter-app file sharing via content://-URIs has definitively broken all multi-file file formats, with no official replacement available.