IMHO, it should be there as soon as you arrive on the site and then reappear on every page load.
I have an old Instagram account that I created over 10 years ago. At the time, I used it for the photo filters. Never cared about the social networking aspect. Just a month ago I logged into it for the first time in forever, and realized I wanted to delete those old posts. Guess what you can't do from the website? Yeah, delete posts. Need the app for that!
A few years ago I had trouble using the Dutch thuisbezorgd food service, I think it didn't allow me to change my address or something and just kept erroring out. I contacted support and they told me to use the app. I told them I don't have a smartphone. They said I was out of luck.