Why doesn't the Todoist app from Firefox Marketplace allow creating an account?
I installed the Todoist app from Firefox Marketplace (https://marketplace.mozilla.org/) on my Android phone, and opened it, only to discover that I had to go to the non-mobile version of the todoist.com web site to create an account.
The sign-up form only has four fields, so displaying them on mobile devices shouldn't be a big problem.
I hadn't used Todoist previously, so I didn't already have an account. I found the Todoist app because it was featured on the Firefox Marketplace. Having to go to a non-mobile site definitely broke the "mobile app" experience for me.