Which one lets them hoover up more data? Probably the desktop app.

Which one lets them display more ads? Probably the site.

For my money, I've always felt like they've tried to force me to use their messenger app on my phone. A while back, desktop/web started asking for a PIN to restore messages. It doesn't always prompt, and sometimes messages are there which you'd think shouldn't be, based on the description of E2EE and the role the PIN plays in it. I did not set any PIN, so I of course don't know it. Resetting the PIN deletes my entire message history.

Which one lets them close off security loopholes scam farms use to automate scam messages and accounts? Probably getting rid of web and desktop.