Treat stable websites as "REST" services?

Now that both Firefox and Chrome can easily be run in headless mode, can we treat stable, never tweaked websites as RESTful services?

For example, consider Mozilla's recently launched service Send - a vanishing file transfer tool. They have not released an API for people to publish files to Send and receive a shareable URL for the uploaded file.

Since I wanted to use Send to deliver VPN You.S.A client certificates to users, I created my own automated script to upload a file to Send and capture the generated shareable URL.

Output:

sai@machine1:~/sandbox/selenium$ node test.js

Uploading /home/sai/sandbox/selenium/a.txt

Shareable send Link = https://send.firefox.com/download/a669b2de9e/#4EqVzlODf5W2oR7T63cTMA

Now, I can easily upload files to Firefox::Send right from my program and share the returned URL with my clients without needing to launch a browser instance.