Locking Elements on Adobe Acrobat DC Pro

Agreed.
So much Adobe kit has loose-ends and missing functionality.

This doesn't seem to be due to commercial imperatives -compartmentalising creative software to ensure users buy more apps.
Instead it seems more due to accumulated legacy issues, missed opportunities and the like.
Illustrator, as someone here once told me with a rather sippy attitude, is not a document creation app, it's a graphics app (despite the fact that it's got PDF export, dozens of typography functions, and document formatting features approaching InDesign! 😆).
I make all my PDF docs in Illustrator and I've found several work-arounds to transcribe them successfully into PDFs just as feature-laden and polished as anything made in InDesign or Acrobat.
I think it's time Adobe got it's act together and overhauled the whole CC stable.
I've been an Adobe user for 30 years and there are still unresolved problems with many CC apps that are almost that old.

Text Boxes and Pictures. So you can't move them but still edit them.