Why cant Acrobat let the user insert the cursor and then type?

Why is it so hard to comment on a pdf?  Why cant Acrobat let the user insert the cursor and then type?  I can insert the cursor and erase alright, but surely adding text can be easier than going to the Comment pane, clicking on the cross-out-add icon, clicking into the document, clicking the cross-out-and-add icon again, and sometimes eventually being able to add text...