I think it was just never implemented. The web page is fairly basic compared to the app, and AFAIK always has been (although I never used it much and haven't had an account in quite a while). Quite a few products are actually app-only now, without even any sort of web or desktop version.
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.