No, definitely not. When games don’t integrate SteamWorks features such as friends lists (or were written by people who accounted for the features to just not be available instead of outright failing), they don’t need Steam.
When the games use GPLed engines, Steam integration may not be legally possible anyway.
Off the top of my head I can immediately name Krita, the painting app by KDE whose Steam release has no Steam integration and runs just fine without.
Bruh, don’t give them ideas for the next price hike!