Thanks @ryanjamurphy for your input and clarification. I am not a programmer. I will leave it to people like you who understand how things work under the cover. 
I would find Obsidian useful as a tool for my academic research if it you were able to highlight PDFs, make notes on the text (OCR?) from the highlights and have this text link back to where they were made in the PDF so that I can see the highlights in context.
In find most PDF editors/readers very frustrating to use because they have you making comments in bubble notes that are hidden the moment you move on to the next comment. I need to be able to have all my comments open because I refer to them when writing the current note. So having the PDF feature in Obsidian would be fantastic!