It's so they can add their help / advertising at the bottom right of the screen.

This is a nit for me in the PDF experience. The browsers I use tend to have no difficulty in rendering the PDF in the browser, but every now and again, you click on a PDF and now it's in your Downloads folder and opening up your OSs PDF viewer. 99% of the time, those PDFs are as disposable as HTML pages that I'd rather not manage and intern on my machine.

It was actually because I didn't want to link to a hubspot url and webflow only supports uploads up to 10mb.