I never used N75, but i had n95, and they’re both running Symbian OS so I assume they were similar at least in software. I had full website browsing (made faster thanks to opera mini), email, file manager. I also had third party apps like Skype, Google maps (doesn’t matter whether you have gps), Gmail. If that’s not a smartphone then I don’t know what is.
Even the wiki you linked to clearly defines it as a smartphone. Why would you argue with that?