Apple takes so long to add cross-platform support despite these services making money with more potential to do so with cross-platform. icloud.com is unusable. Keychain is available only on Mac and iPhone and restricted to Safari.

I understand they are trying to lock-in users to their platform / devices but there would be more users if cross-platform versions are available making more money for them eventually.

It's not like consumers are buying a Mac or iPhone because Apple Music experience is better, or iCloud experience is better.